Octreotide treatment of severe diabetic diarrhoea.
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Adult↗
Biomedical subjects
F Alford
Publications and source records attributed to F Alford.
Glucose-mediated glucose disposal in insulin-resistant normoglycemic relatives of type 2 diabetic patients.
With the aim of investigating glucose-mediated glucose disposal (glucose effectiveness [GE]) in 15 (3 female and 12 male subjects) insulin-resistant normoglycemic relatives of patients with type 2 diabetes (DM2), and 15 age-, sex-, and BMI-matched control subjects without a family history of DM2, we performed 2 studies: 1) a 5-h euglycemic near-normoinsulinemic pancreatic clamp with somatostatin (360 microg/h), insulin (0.25 mU x kg(-1) x min(-1)), glucagon (0.5 ng x kg(-1) x min(-1)), growth hormone (6 ng x kg(-1) x min(-1)), and tritiated glucose infusion and indirect calorimetry; and 2) on a separate day, an identical 5-h clamp but at hyperglycemia (approximately 12 mmol/l) over the last 2 h. Fasting plasma insulin (PI) concentrations were elevated in the relatives compared with control subjects (49 +/- 6 vs. 32 +/- 5 pmol/l, P < 0.04), whereas plasma glucose (PG) was not (5.6 +/- 0.1 vs. 5.5 +/-0.1 mmol/l). At the end (i.e., 4.5-5.0 h) of the euglycemic clamp (PG, 6.1 +/- 0.4 vs. 5.6 +/- 0.1 mmol/l; PI, 78 +/- 5 vs. 73 +/-6 pmol/l), peripheral glucose uptake (Rd(euglycemia)) was decreased in the relatives (2.93 +/- 0.08 vs. 3.70 +/-0.23 mg x min(-1) x kg(-1) fat free mass [FFM], P < 0.005), due to a decreased nonoxidative glucose disposal (0.83 +/-0.21 vs. 1.62 +/- 0.19 mg x min(-1) x kg(-1) FFM, P < 0.01), but hepatic glucose production (HGP) was increased (1.97 +/-0.19 vs. 1.50 +/- 0.13 mg x min(-1) x kg(-1) FFM, P < 0.05). At the matched end of the hyperglycemic clamp (PG, 12.7 +/-0.2 vs. 12.6 +/- 0.2 mmol/l; PI, 87 +/- 5 vs. 78 +/- 7 pmol/l), peripheral glucose disposal (Rd(hyperglycemia)) (5.52 +/- 0.22 vs. 5.92 +/- 0.29 mg x min(-1) x kg(-1) FFM, NS), nonoxidative glucose disposal (2.93 +/- 0.18 vs. 2.78 +/- 0.25 mg x min(-1) x kg(-1) FFM, NS), and HGP(hyperglycemia) (1.20 +/- 0.09 vs. 1.37 +/-0.23 mg x min(-1) x kg(-1) FFM, NS) were all identical. When the effectiveness of glucose itself on glucose uptake and production [(Rd(hyperglycemia) - Rd(euglycemia))/deltaPG and (HGP(euglycemia)- HGP(hyperglycemia))/deltaPG] was calculated, the relatives had a 22% increase in peripheral uptake (0.022 +/- 0.002 vs. 0.018 +/- 0.002 mg x min(-1) x kg(-1) FFM per mg/dl), due to a significantly increased nonoxidative glucose metabolism and enhanced suppression of HGP (0.0076 +/- 0.0021 vs. 0.0011 +/- 0.0022 mg x min(-1) x kg(-1) FFM per mg/dl, P < 0.05). In conclusion, in insulin-resistant relatives of DM2 patients, whole-body glucose-mediated glucose disposal is increased by GE enhancement of the muscle nonoxidative glucose pathway and by GE enhancement of the suppression of HGP. These mechanisms may represent a compensatory mechanism to the ongoing insulin resistance of these relatives.
Adult↗
Intracellular skeletal muscle glucose metabolism is differentially altered by dexamethasone treatment of normoglycemic relatives of type 2 diabetic patients.
Young first-degree relatives of type 2 diabetic patients are insulin-resistant, with the insulin resistance mainly located in skeletal muscle due to decreased insulin-induced nonoxidative glucose metabolism and muscle glycogen synthase activation. We investigated whether the mechanism differs for dexamethasone (dex)-induced insulin resistance in first-degree relatives of type 2 diabetics versus healthy control subjects by quantifying intracellular glucose processing in muscle biopsies taken before and after 5 days of dex treatment (4 mg/d) in 20 normal glucose-tolerant relatives of type 2 diabetic patients and 20 matched controls (age, 29.4 +/- 1.7 v 29.4 +/- 1.6 years; body mass index, 25.1 +/- 1.0 v 25.1 +/- 0.9 kg/m2). In addition, an intravenous glucose tolerance test (IVGTT) combined with continuous indirect calorimetry was performed. Following 5 days of dex treatment, glucose tolerance deteriorated in both the relatives and the control subjects. Fasting dry-weight muscle glucose and fasting intracellular muscle glucose concentrations increased in response to dex only in the relatives (2.43 +/- 0.21 v 2.97 +/- 0.26 mmol/kg dry weight, P < .05; 0.28 +/- 0.07 v 0.45 +/- 0.08 mmol/L intracellular water, P < .05); no increases were observed in the control subjects. Fasting dry-weight muscle lactate also increased post-dex only in the relatives (7.37 +/- 0.40 v 10.77 +/- 1.22 mmol/kg dry weight, P < .001). Both basal muscle glucose and lactate concentrations from the IVGTT study correlated with the 2-hour post-dex glucose value obtained during the OGTT study in the relatives (R = .76 and R = .74, respectively, both P < .0001) but not in the control subjects. Basal intramuscular glycogen synthase activity decreased approximately 25% in both the relatives and control subjects post-dex; the decrement was significant (P < .01) only in control subjects. Indirect calorimetry during the post-dex IVGTT demonstrated increased glucose oxidation (P < .03) and reduced lipid oxidation (P < .03) in the relatives only. We postulate that the insulin resistance induced by dex in first-degree relatives of type 2 diabetic patients is associated with a preferential channeling of glucose into the glycolytic pathway (increased glucose oxidation and lactate production), probably associated with a preexisting downregulation of the glycosen synthase pathway.
Adult↗
Insulin secretion in growth hormone-deficient adults: effects of 24 months' therapy and five days' acute withdrawal of recombinant human growth hormone.
Beta-cell function in growth hormone (GH)-deficient (GHD) adults is poorly documented. Beta-cell function was therefore studied in 10 GHD adults (age, 40+/-3 years; weight, 79.3+/-4.8 kg; body mass index [BMI], 27.5+/-1.3 kg x m(-2)) before and after 6- and 24-month recombinant human GH (rhGH) therapy (0.24 IU x kg(-1) x wk(-1)) compared with 10 age-, sex-, weight-, and BMI-matched control subjects. With rhGH therapy, fat-free mass (FFM) increased (48.2+/-4.9, 52.5+/-4.8, and 59+/-6.8 kg, respectively) and fat mass (FM) decreased (33.8%+/-2.8%, 28.0%+/-3.0%, and 29.4%+/-2.5%, respectively), as did serum cholesterol. Oral glucose tolerance initially deteriorated at 6 months, but improved toward the control value by 24 months. Fasting insulin (FI) increased significantly, as did the acute insulin response to oral glucose (deltaAIR(OGTT)/deltaG) at 30 minutes (FI: pretreatment 9.8+/-0.8, 6 months, 14.0+/-1.8, 24 months 12.5+/-1.6 v control 11.4+/-1.9 mU x L(-1); deltaAIR(OGTT)/deltaG: pretreatment 201+/-24, 6 months 356+/-41, 24 months 382+/-86 v control 280+/-47 mU x mmol(-1)). However, the acute insulin response to intravenous (IV) glucose (AIR(G)) and IV glucagon at euglycemia and hyperglycemia did not change with rhGH therapy and were similar to the control group values. Importantly, the expected reciprocal relationships (as observed for the control group) between the various insulin secretory parameters and insulin sensitivity (SI) either were not present or were statistically weak in GHD subjects, despite the 35% decrease in SI by 24 months of rhGH therapy. In particular, over time, there was an attenuation of insulin secretion with respect to the ongoing insulin resistance with rhGH therapy, particularly for AIR(G) at 24 months. After 5 days of rhGH withdrawal, insulin secretion decreased and SI improved in GHD subjects. It is concluded that the current long-term rhGH treatment regimens appear to impact on insulin secretion such that the normal relationships between insulin secretion and SI are altered despite the favorable impact on body composition and serum lipid profiles.
Adult↗
The effect of 24 months recombinant human growth hormone (rh-GH) on LDL cholesterol, triglyceride-rich lipoproteins and apo [a] in hypopituitary adults previously treated with conventional replacement therapy.
Hypopituitary adults receiving conventional hormone replacement therapy are reported to have increased cardiovascular mortality. Previous studies indicate that these patients have several abnormalities in lipoprotein metabolism, including reduced low density lipoprotein (LDL) uptake and impaired metabolism of triglyceride-rich lipoproteins. The effects of 24 months of 0.21 IU/kg per week recombinant growth hormone (rh-GH) on the lipoprotein profiles of 22 GH-deficient adults were studied. Samples were collected after a 12-h fast at baseline and 24 months. Total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, LDL cholesterol, apolipoprotein (apo) A, apo B and apo [a] were determined by routine laboratory methods. LDL particle size was determined by non-denaturing gradient gel electrophoresis. Visceral adiposity was determined by dual energy X-ray absorptiometry (DEXA). Insulin sensitivity was measured in a subset of 17 subjects using a two-stage hyperinsulinaemic-euglycaemic clamp. Significant reductions were observed in total cholesterol (5.3 +/- 0. 17 vs 4.9 +/- 0.23 mmol/l;P<0.05) and LDL cholesterol (3.4 +/- 0.17 vs 2.9 +/- 0.17 mmol/l; P<0.001) at 24 months when compared to baseline. No significant changes were observed in triglyceride level, HDL cholesterol level, apo B, apo A and LDL size. A significant increase in apo [a] [160 (96-416) vs 204 (127-534) U/l;P<0.05] was observed which appeared to be dose-dependent. Visceral adiposity was reduced significantly. Insulin sensitivity did not alter significantly. Replacement for 24 months with rh-GH has a differential effect on the lipid profile with a decrease in LDL, but little effect upon the metabolism of triglyceride-rich lipoproteins, manifested by unchanged triglyceride, HDL cholesterol levels and LDL size, despite the reduction in visceral adiposity. Conversely, apo [a], an independent risk factor for cardiovascular disease was increased. The ultimate effect of GH therapy upon cardiovascular mortality remains to be determined and may be dose-related.
Adult↗
The Australian Multicenter Trial of Growth Hormone (GH) Treatment in GH-Deficient Adults.
GH treatment in adults with GH deficiency has numerous beneficial effects, but most studies have been small. We report the results of an Australian multicenter, randomized, double-blind, placebo-controlled trial of the effects of recombinant human GH treatment in adults with GH deficiency. GH deficiency was defined as a peak serum GH of < 5 mU/liter in response to insulin-induced hypoglycemia. Patients were randomly assigned to receive either GH (0.125 U/kg per week for 1 month and 0.25 U/kg per week for 5 months) or placebo. After 6 months, all patients received GH. The primary end points were biochemical responses, body composition, quality of life, and safety. One hundred sixty-six patients (72 females and 91 males) with a mean age of 40 +/- 1 yr (+/- SEM; range 17-67 yr) were recruited. Serum insulin-like growth factor-I (IGF-I) increased from a standard deviation score of -2.64 +/- 0.27 (range -8.8 +3.82; n = 78) to +1.08 +/- 2.87 (range -7.21 to +6.42) at 6 months in the GH/GH group; 38% of the whole group were above the age-specific reference range following treatment [17.6% and 68.9% with subnormal (< 2 SD) or normal (+/- 2 SD) pretreatment levels, respectively]. Fasting total cholesterol (P = 0.042) and low-density lipoprotein cholesterol (P = 0.006) decreased over the first 6 months. Fat-free mass increased in the first 6 months whether measured by bioelectrical impedance (P < 0.001) or dual energy x-ray absorptiometry (DEXA; P < 0.001). Total-body water increased in the first 6 months whether measured by bioelectrical impedance (P < 0.001) or deuterium dilution (P = 0.002). Fat mass measured by DEXA (P < 0.001), skinfold thicknesses (P < 0.001), and waist/hip ratio (P = 0.001) decreased in the first 6 months. Most changes in body composition were complete by 3 months of treatment and maintained to 12 months. Whole-body bone mineral density (BMD) (by DEXA) was unaffected by GH treatment. Self-reported quality of life was considered good before treatment, and beneficial treatment effects were observed for energy, pain, and emotional reaction as assessed by the Nottingham Health Profile. In the initial 6 months, adverse effects were reported by 84% of patients in the GH and 75% in the placebo group, with more symptoms relating to fluid retention in the GH group (48% vs. 30%; P = 0.016). Such symptoms were mild and resolved in 70% of patients despite continued treatment. Resting blood pressure did not change over the initial 6 months. In summary, GH treatment in adults with GH deficiency resulted in 1) prominent increases in serum IGF-I at the doses employed, in some cases to supraphysiological levels; 2) modest decreases in total- and low-density lipoprotein cholesterol, together with substantial reductions in total-body and truncal fat mass consistent with an improved cardiovascular risk profile; 3) substantial increases in lean tissue mass; and 4) modest improvements in perceived quality of life. The excessive IGF-I response and side-effect profile suggests that lower doses of GH may be a required for prolonged GH treatment in adults with severe GH deficiency.
Adult↗
Defects of insulin action and skeletal muscle glucose metabolism in growth hormone-deficient adults persist after 24 months of recombinant human growth hormone therapy.
We have previously reported that GH-deficient (GHD) adults are severely insulin resistant. In the present study, we determined the effects of 6 months (n = 7) and 24 months (long-term; n = 11) of recombinant human GH (rhGH) therapy (approximately 0.22 IU/kg.week) on body composition and fasting biochemical (including lipid) parameters, and baseline and insulin-stimulated: 1) rates of hepatic glucose production, total glucose disposal (Rd), total glycolysis (GF) and glucose storage (GS); and 2) skeletal muscle glucose processing [using the euglycemic-hyperinsulinemic (approximately 60 mU/L) clamp technique with tritiated glucose infusion coupled with skeletal muscle biopsies]. To allow baseline comparison, these measurements were also obtained from 10 control subjects matched to the pretreated GHD adults for age, sex, and body mass index. Long-term rhGH therapy in GHD adults induced significant improvements in fat mass, abdominal fat mass and fat free mass, and reductions in fasting cholesterol and low-density lipoprotein-cholesterol levels (P < 0.05-0.01 vs. pretreatment values). However, there was a significant increase in fasting insulin (13.1 +/- 0.9 vs. 8.6 +/- 1.1 mU/L; P < 0.01) and connecting peptide (0.56 +/- 0.05 vs. 0.41 +/- 0.06 nmol/L; P < 0.05). Although rates of baseline hepatic glucose production, GF, and GS were unchanged, the insulin-stimulated increment (delta) in Rd, GF, and GS remained markedly attenuated in the long-term rhGH-treated GHD adults [pretreatment: delta Rd 16.6 +/- 3.4, delta GF 3.0 +/- 1.2, delta GS 13.6 +/- 3.0 vs. 24 months of rhGH: delta Rd 17.2 +/- 3.3, delta GF 3.1 +/- 0.9, delta GS 14.1 +/- 2.5 vs. controls: delta Rd 42.6 +/- 4.3, delta GF 9.2 +/- 1.9, delta GS 35.9 +/- 4.5 mumol/kg fat free mass.min; P < 0.05-0.01 vs. controls]. Additionally, there was a sustained reduction in the insulin-stimulated skeletal muscle glycogen synthase fractional velocity (pretreatment: 0.29 +/- 0.03 vs. 24 months of rhGH: 0.24 +/- 0.03 vs. controls: 0.48 +/- 0.04; both P < 0.05 vs. controls), which was accompanied by a sustained 44% decrease in baseline glycogen content and a 70% increase in baseline im glucose concentrations in the presence of low-to-normal glucose 6-phosphate levels and persisting euglycemia. Stepwise regression analysis revealed that body weight and fasting free fatty acid and high-density lipoprotein (HDL)-cholesterol accounted for 82% of the variance in the insulin sensitivity index in long-term rhGH-treated adults, and that the 24-month fasting insulin-like growth factor 1 was a negative predictor of the change in insulin sensitivity (r = -0.82; P < 0.01). In conclusion, despite improvements in body composition and lipid profiles, the severe defects of in vivo insulin sensitivity and skeletal muscle intracellular glucose phosphorylation and glycogen synthase activity, which are associated with modestly elevated insulin-like growth factor 1 levels, normal free fatty acid levels, and the development of hyperinsulinemia, persist with long-term rhGH therapy.
Adult↗
Mutation analysis of the MEN1 gene in multiple endocrine neoplasia type 1, familial acromegaly and familial isolated hyperparathyroidism.
Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant disease characterized by neoplasia of the parathyroid glands, the endocrine pancreas, and the anterior pituitary gland. In addition, families with isolated endocrine neoplasia, notably familial isolated hyperparathyroidism (FIHP) and familial acromegaly, have also been reported. However, whether these families constitute MEN 1 variants or separate entities remains speculative as the genetic bases for these diseases are unclear. The gene for MEN 1 has recently been cloned and characterized. Using single strand conformation analysis (SSCA) and sequencing, we performed mutation analysis in: a) a total of 55 MEN 1 families from 7 countries, b) 13 isolated MEN 1 cases without family history of the disease, c) 8 acromegaly families, and d) 4 FIHP families. Mutations were identified in 27 MEN 1 families and 9 isolated cases. The 22 different mutations spread across most of the 9 translated exons and included frameshift (11), nonsense (6), splice (2), missense mutations (2), and in-frame deletions (1). Among the 19 Finnish MEN 1 probands, a 1466del12 mutation was identified in 6 families with identical 11q13 haplotypes and in 2 isolated cases indicating a common founder. One frameshift mutation caused by 359del4 (GTCT) was found in 1 isolated case and 4 kindreds of different origin and haplotypes; this mutation therefore represents a common "warm" spot in the MEN1 gene. By analyzing the DNA of the parents of an isolated case one mutation was confirmed to be de novo. No mutation was found in any of the acromegaly and small FIHP families, suggesting that genetic defects other than the MEN1 gene might be involved and that additional such families need to be analyzed.
Acromegaly↗
Risk and mechanism of dexamethasone-induced deterioration of glucose tolerance in non-diabetic first-degree relatives of NIDDM patients.
We tested the hypothesis that glucose intolerance develops in genetically prone subjects when exogenous insulin resistance is induced by dexamethasone (dex) and investigated whether the steroid-induced glucose intolerance is due to impairment of beta-cell function alone and/or insulin resistance. Oral glucose tolerance (OGTT) and intravenous glucose tolerance tests with minimal model analysis were performed before and following 5 days of dex treatment (4 mg/day) in 20 relatives of non-insulin-dependent diabetic (NIDDM) patients and in 20 matched control subjects (age: 29.6 +/- 1.7 vs 29.6 +/- 1.6 years, BMI: 25.1 +/- 1.0 vs 25.1 +/- 0.9 kg/m2). Before dex, glucose tolerance was similar in both groups (2-h plasma glucose concentration (PG): 5.5 +/- 0.2 [range: 3.2-7.0] vs 5.5 +/- 0.2 [3.7-7.4] mmol/l). Although insulin sensitivity (Si) was significantly lower in the relatives before dex, insulin sensitivity was reduced to a similar level during dex in both the relatives and control subjects (0.30 +/- 0.04 vs 0.34 +/- 0.04 10(-4) min(-1) per pmol/l, NS). During dex, the variation in the OGTT 2-h PG was greater in the relatives (8.5 +/- 0.7 [3.9-17.0] vs 7.5 +/- 0.3 [5.7-9.8] mmol/l, F-test p < 0.05) which, by inspection of the data, was caused by seven relatives with a higher PG than the maximal value seen in the control subjects (9.8 mmol/l). These "hyperglycaemic" relatives had diminished first phase insulin secretion (O1) both before and during dex compared with the "normal" relatives and the control subjects (pre-dex O1: 12.6 +/- 3.6 vs 26.4 +/- 4.2 and 24.6 +/- 3.6 (p < 0.05), post-dex O1: 22.2 +/- 6.6 vs 48.0 +/- 7.2 and 46.2 +/- 6.6 respectively (p < 0.05) pmol x l(-1) x min(-1) per mg/dl). However, Si was similar in "hyperglycaemic" and "normal" relatives before dex (0.65 +/- 0.10 vs 0.54 +/- 0.10 10(-4) x min(-1) per pmol/l) and suppressed similarly during dex (0.30 +/- 0.07 vs 0.30 +/- 0.06 10(-4) x min(-1) per pmol/l). Multiple regression analysis confirmed the unique importance of low pre-dex beta-cell function to subsequent development of high 2-h post-dex OGTT plasma glucose levels (R2 = 0.56). In conclusion, exogenous induced insulin resistance by dex will induce impaired or diabetic glucose tolerance in those genetic relatives of NIDDM patients who have impaired beta-cell function (retrospectively) prior to dex exposure. These subjects are therefore unable to enhance their beta-cell response in order to match the dex-induced insulin resistant state.
Adult↗
Intracellular glucose and fat metabolism in identical twins discordant for non-insulin-dependent diabetes mellitus (NIDDM): acquired versus genetic metabolic defects?
UNLABELLED: Intracellular glucose and lipid metabolism was studied in 12 identical twin pairs discordant for non-insulin-dependent (Type 2) diabetes mellitus (NIDDM) and 13 control subjects without family history of diabetes during low (baseline) and high plasma insulin concentrations, using the hyperinsulinaemic clamp technique combined with indirect calorimetry, tritiated water glycolytic flux rates and biopsy skeletal muscle glycogen synthase activity determinations. Baseline and insulin stimulated rates of lipid oxidation were elevated--and glucose oxidation decreased--in the NIDDM twins compared with the non-diabetic co-twins and controls (all p < 0.05). Baseline and insulin stimulated rates of glucose and lipid oxidation were similar in non-diabetic twins and controls. Exogenous glycolytic flux was decreased in NIDDM twins compared with both their non-diabetic co-twins and controls during clamp insulin measurements (p < 0.02), but similar in all study groups during baseline measurements. Insulin stimulated glucose disposal, exogenous glucose storage (glucose disposal-exogenous glycolytic flux) and skeletal muscle glycogen synthase activity were all significantly decreased in NIDDM twins compared with both their non-diabetic co-twins and controls. Furthermore, glucose disposal and glucose storage were decreased in the non-diabetic twins (n = 12) compared with controls (p < 0.05 both). However, insulin stimulated fractional skeletal muscle glycogen synthase activity was not significantly decreased in non-diabetic twins compared with controls. IN CONCLUSION: (1) the glucose fatty acid cycle plays a major role in the secondary--but not the primary--abnormalities of glucose metabolism in NIDDM; (2) insulin resistance in non-diabetic identical co-twins of NIDDM patients is restricted exclusively to the pathway of exogenous glucose storage; (3) however, the decreased glucose storage is not explained solely by an impairment of insulin stimulated skeletal muscle glycogen synthase activity; and finally (4) the impairment of skeletal muscle glycogen synthase activity in NIDDM has an apparent non-genetic component and can be escaped (or postponed) in individuals (twins) with a 100% genetic predisposition to NIDDM.
Analysis of Variance↗
Glucose processing during the intravenous glucose tolerance test.
The impact of the dynamic changes in plasma glucose and insulin levels observed during a frequently sampled intravenous (IV) glucose tolerance test (FSIGT) on whole-body glucose processing and muscle glycogen metabolism is not known. Paired randomized FSIGTs were performed in eight healthy subjects (age, 31 years; range, 28 to 35; BMI, 25.4 kg/m2; range, 22.3 to 32.1), one with muscle biopsy samples and one without. The mean time average (0- to 40- and 0- to 120-minute) insulin levels during the test were 26.6 and 11.4 mU/1, respectively. Glucose oxidation increased following the IV glucose bolus (basal 1.34 +/- 0.21 v mean value at 0 to 120 minutes 2.09 +/- 0.22 mg/kg fat-free mass [FFM]/min, P < .02). In contrast, fractional glucose-6-phosphate [G-6-P]) (0.1/10 mmol/L) skeletal muscle glycogen synthase activity in muscle biopsies obtained before and following the IV glucose bolus (-30, 30,60, and 120 minutes, respectively) were unchanged (38.1% +/- 2.3%, 38.3% +/- 2.9%, 38.1% +/- 2.3%, 35.4% +/- 2.3%, NS). Skeletal muscle glycogen concentration decreased slightly (449 +/- 54, 439 +/- 55, and 383 +/- 29, and 438 +/- 48 mmol/kg dry weight, P =.05), indicating no net storage of glucose into glycogen during the FSIGT. G-6-P decreased (0.77 +/- 0.08, 0.64 +/- 0.07, 0.66 +/- 0.07, and 0.54 +/- 0.04 mmol/kg dry weight, P < .05). Levels of the insulin-regulatable glucose transporter, GLUT-4, were unchanged. Insulin sensitivity (Si), glucose effectiveness, and insulin secretion parameters (01 and 02) were not affected by the muscle biopsy procedure. In conclusion, the FSIGT is associated predominantly with increased whole-body glucose oxidation with no apparent activation of muscle glucose storage as glycogen. Thus, the Si measured by the FSIGT, although similar in magnitude to the clamp-derived parameter, represents primarily glucose oxidation, in contrast to the euglycemic clamp, which involves glucose oxidation and storage.
Adult↗
Insulin resistance in growth hormone-deficient adults: defects in glucose utilization and glycogen synthase activity.
Fourteen GH-deficient (GHD) adults were compared with 12 age-, sex-, and body mass index-matched control subjects using a baseline tritiated glucose equilibration period and euglycemic-hyperinsulinemic (approximately 55 mU/L) clamp in conjunction with paired muscle biopsies for measurement of glycogen synthase fractional velocity (FV0.1). Despite similar basal rates of total glucose disposal (Rd), there was a 64% reduction in the insulin-stimulated rise (delta) in Rd in the GHD adults compared to that in controls [16.6 +/- 2.8 vs. 44.7 +/- 6.0 mumol/kg fat free mass (FFM)/min; P < 0.001], which was mainly due to a decreased glucose storage (GS) rate (delta GS, 12.6 +/- 2.9 vs. 39.5 +/- 7.5 mumol/kg FFM/min; P < 0.01). Furthermore, the insulin sensitivity indexes of Rd (0.39 +/- 0.07 vs. 0.85 +/- 0.11; P < 0.05) and GS (0.25 +/- 0.07 vs. 0.72 +/- 0.13 mumol/kg FFM/min per mU/L; P < 0.02) were reduced in GHD adults compared to the control values. The insulin sensitivity of the glycolytic pathway was also reduced by approximately 50% in GHD adults (P = 0.07 vs. controls). Insulin-stimulated FV0.1 was decreased in GHD adults (0.31 +/- 0.02 vs. 0.47 +/- 0.03; P < 0.005) despite similar basal FV0.1. Using multiple and stepwise regression analysis, duration of GH deficiency, fasting triglycerides and fasting insulin accounted for 67% of the variance in the insulin sensitivity index of Rd. In conclusion, the severe insulin resistance in GHD adults is mainly due to the inhibition of the GS pathway and glycogen synthase activity in peripheral tissues, which is related to the duration of GH deficiency, fasting triglycerides, and fasting insulin.
Adult↗
Low density lipoprotein particle size in hypopituitary adults receiving conventional hormone replacement therapy.
Adults receiving conventional replacement therapy for hypopituitarism are known to have increased cardiovascular mortality. The aim of this study was to assess the lipid profiles of 30 hypopituitary adults compared with 2 case control groups, 1 matched for age, sex, and body mass index (BMI) and the second matched for age and sex only with a BMI representative of the general population. Fasting lipids, lipoproteins, and apoproteins (Apo) were determined by routine methods. Low density lipoprotein (LDL) particle size was determined by nondenaturing gradient gel electrophoresis. LDL size was significantly smaller in the hypopituitary group (25.9 +/- 0.1 nm) than in the BMI-matched (26.2 +/- 0.1 nm; P < 0.05) and standard control (26.3 +/- 0.1 nm; P < 0.01) groups. High density lipoprotein cholesterol levels in the hypopituitary group were significantly lower than those in the BMI-matched control group (1.13 +/- 0.06 vs. 1.34 +/- 0.06 mmol/L; P < 0.05) and the standard control group (1.38 +/- 0.06 mmol/L; P < 0.005). Apo A1 levels were also lower compared with those in the BMI-matched (122 +/- 6 vs. 137 +/- 4 mg/dL; P < 0.05) and the standard (143 +/- 4 mg/dL; P < 0.005) control groups. There was a trend toward higher triglyceride levels when the hypopituitary subjects were compared with the standard control group [1.4 (95% CI, 1.3-2.2) vs. 1.0 (95% CI, 0.9-1.4) mmol/L; P = 0.06]. These differences were more marked in the female subjects studied. No significant differences were noted in total cholesterol, LDL cholesterol, or Apo B levels. We conclude that hypopituitary patients receiving conventional replacement therapy have an atherogenic lipid profile characterized by small dense LDL, decreased high density lipoprotein cholesterol, and increased triglyceride levels, which may contribute to the excess cardiovascular mortality in this group.
Adult↗
In vivo glucose metabolism, insulin secretion and, insulin action in Europids with non-insulin-dependent diabetes mellitus (NIDDM) and their first-degree relatives.
In this review we will mainly concentrate on the most common form of NIDDM in Europe, namely the form linked to overweight, arterial hypertension, dyslipoproteinaemia and coronary heart disease (CHD)-the Insulin Resistance Syndrome (IRS). This form of NIDDM seems to be growing epidemically world wide following the industrial growth or the 'cocacolanization', as it has been mentioned. Around 2-3% of the population in Europe suffers from this disease, but for subjects beyond 60 years of age the prevalence is 5-20%. Thus, we face an enormous economical, social, and humanitarian challenge. Therefore it is important to continue the research on aetiology and pathophysiology of this syndrome. The results of treatment of NIDDM patients (often started at 60 years of age) have been rather disappointing; even properly treated NIDDM patients develop substantial complications, especially macroangiopathy. Coronary heart disease is the main cause of death in these patients and the overall mortality rate in NIDDM patients is 3-4 times higher than in comparable non diabetic-subjects. Furthermore, several complications may already be present at the diagnosis of the disease, which indicate that macroangiopathy may not be secondary to the diabetic state itself, but rather a part of the NIDDM phenotype. Based on these findings it seems obvious that the IRS must be diagnosed in the prediabetic states before macroangiopathy has started or reached a clinically manifest level. In this review, therefore, we will discuss the metabolic background of NIDDM and especially focus on the pathophysiological mechanisms leading to hyperglycaemia, i.e. alterations in glucose effectiveness, insulin action and insulin secretion in prediabetic states.
Adult↗
Multiple defects of both hepatic and peripheral intracellular glucose processing contribute to the hyperglycaemia of NIDDM.
Non-insulin-dependent diabetic (NIDDM) patients were studied during a modified euglycaemic state when fasting hyperglycaemia was normalized by a prior (-210 to -150 min)--and later withdrawn (-150-0 min)--intravenous insulin infusion. Glucose metabolism was assessed in NIDDM patients (n = 10) and matched control subjects (n = 10) using tritiated glucose turnover rates, indirect calorimetry and skeletal muscle glycogen synthase activity determinations. Total and non-oxidative exogenous glycolytic flux rates were measured using appearance rates of tritiated water. A + 180 min euglycaemic hyperinsulinaemic (40 mU.m-2.min-1) clamp was performed to determine the insulin responsiveness of the various metabolic pathways. Plasma glucose concentration increased spontaneously during baseline measurements in the NIDDM patients (-120 to 0 min: 4.8 +/- 0.3 to 7.0 +/- 0.3 mmol/l; p < 0.01), and was primarily due to an elevated rate of hepatic glucose production (3.16 +/- 0.13 vs 2.51 +/- 0.16 mg.kg FFM-1.min-1; p < 0.01). In the NIDDM subjects baseline glucose oxidation was decreased (0.92 +/- 0.17 vs 1.33 +/- 0.14 mg.kg FFM-1.min-1; p < 0.01) in the presence of a normal rate of total exogenous glycolytic flux and skeletal muscle glycogen synthase activity. The simultaneous finding of an increased lipid oxidation rate (1.95 +/- 0.13 vs 1.61 +/- 0.07 mg.kg FFM-1.min-1; p = 0.05) and increased plasma lactate concentrations (0.86 +/- 0.05 vs 0.66 +/- 0.03 mmol/l; p = 0.01) are consistent with a role for both the glucose-fatty acid cycle and the Cori cycle in the maintenance and development of fasting hyperglycaemia in NIDDM during decompensation. Insulin resistance was demonstrated during the hyperinsulinaemic clamp in the NIDDM patients with a decrease in the major peripheral pathways of intracellular glucose metabolism (oxidation, storage and muscle glycogen synthase activity), but not in the pathway of non-oxidative glycolytic flux which was not completely suppressed during insulin infusion in the NIDDM patients (0.55 +/- 0.15 mg.kg FFM-1.min-1; p < 0.05 vs 0; control subjects: 0.17 +/- 0.29; NS vs 0). Thus, these data also indicate that the defect(s) of peripheral (skeletal muscle) glucose processing in NIDDM goes beyond the site of glucose transport across the cell membrane.
Biopsy↗
Pathogenesis of type 2 (non-insulin-dependent) diabetes mellitus: the role of skeletal muscle glucose uptake and hepatic glucose production in the development of hyperglycaemia. A critical comment.
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Biological Transport↗
Aneuploid islet cell tumor with late metastasis.
An unusual case of insulin producing islet cell tumor is reported which recurred after a 16 yr interval. In most instances malignancy of islet cell tumors is impossible to assess morphologically or functionally but depends on the recognition of metastases. Nuclear DNA analysis provides significant prognostic and biological information in a number of solid human tumors. Retrospective computerized nuclear image analysis of the primary tumor in the present case showed an aneuploid DNA profile similar to that seen in the metastasis. It appears that ploidy studies may be useful in predicting malignant potential of islet cell tumors.
Adenoma, Islet Cell↗
Increased glucose effectiveness in normoglycemic but insulin-resistant relatives of patients with non-insulin-dependent diabetes mellitus. A novel compensatory mechanism.
20 normoglycemic first degree relatives of non-insulin-dependent diabetes mellitus (NIDDM) patients were compared with 20 matched subjects without any family history of diabetes using the intravenous glucose tolerance test with minimal model analysis of glucose disappearance and insulin kinetics. Intravenous glucose tolerance index (Kg) was similar in both groups (1.60 +/- 0.14 vs 1.59 +/- 0.18, x 10(-2) min-1, NS). However, insulin sensitivity (Si) was reduced (3.49 +/- 0.43 vs 4.80 +/- 0.61, x 10(-4) min-1 per mU/liter, P = 0.05), whereas glucose effectiveness (Sg) was increased (1.93 +/- 0.14 vs 1.52 +/- 0.16, x 10(-2) min-1, P < 0.05) in the relatives. Despite insulin resistance neither fasting plasma insulin concentration (7.63 +/- 0.48 vs 6.88 +/- 0.45, mU/liter, NS) nor first phase insulin responsiveness (Phi1) (3.56 +/- 0.53 vs 4.13 +/- 0.62, mU/liter min-1 per mg/dl, NS) were increased in the relatives. Phi1 was reduced for the degree of insulin resistance in the relatives so that the Phi1 x Si index was lower in the relatives (11.5 +/- 2.2 vs 16.7 +/- 2.0, x 10(-4) min-2 per mg/dl, P < 0.05). Importantly, glucose effectiveness correlated with Kg and with basal glucose oxidation but not with total glucose transporter 4 (GLUT4) content in a basal muscle biopsy. In conclusion we confirm the presence of insulin resistance in first degree relatives of NIDDM patients. However, insulin secretion was altered and reduced for the degree of insulin resistance in the relatives, whereas glucose effectiveness was increased. We hypothesize that increased glucose effectiveness maintains glucose tolerance within normal limits in these "normoinsulinemic" relatives of NIDDM patients.
Adult↗