PubMed Health⌕ Search

Biomedical subjects

B Thorsteinsson

Publications and source records attributed to B Thorsteinsson.

At least 19 recordsLinked to original sources
PubMed2006

Frequency and risk factors of severe hypoglycaemia in insulin-treated Type 2 diabetes: a cross-sectional survey.

AIMS: The reported risk of severe hypoglycaemia in insulin-treated Type 2 diabetes is highly variable and few studies have evaluated the influence of risk factors. We assessed the incidence and the influence of potential risk factors for severe hypoglycaemia in a questionnaire survey in subjects with insulin-treated Type 2 diabetes receiving currently recommended multifactorial intervention. METHODS: Consecutive patients with insulin-treated Type 2 diabetes (n = 401) completed a questionnaire about occurrence of hypoglycaemia in the past, hypoglycaemia awareness and socio-demographic factors. A zero-inflated negative binomial model was used to assess the influence of potential risk factors on the rate of severe hypoglycaemia. RESULTS: The overall incidence of severe hypoglycaemia in the preceding year was 0.44 episodes/person year. Sixty-six (16.5%) patients had experienced at least one event. The risk of any episode of severe hypoglycaemia positively correlated with impaired hypoglycaemia awareness, being married and long duration of diabetes. The risk of repeated episodes of severe hypoglycaemia positively correlated with the presence of peripheral neuropathy, while long duration of diabetes prior to insulin treatment and treatment with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor antagonists (ARBs) were associated with reduced risk. C-peptide concentration and HbA1c were not associated with the risk of severe hypoglycaemia. CONCLUSIONS: In this cohort of insulin-treated Type 2 diabetic patients, the incidence of severe hypoglycaemia is higher than reported in most studies, corresponding to about one-third of that in Type 1 diabetes. Impaired hypoglycaemia awareness is the most important risk factor for severe hypoglycaemia.

Adult↗
PubMed2005

Association between plasma activities of semicarbazide-sensitive amine oxidase and angiotensin-converting enzyme in patients with type 1 diabetes mellitus.

AIMS/HYPOTHESIS: Plasma semicarbazide-sensitive amine oxidase (SSAO) is elevated in patients with type 1 and type 2 diabetes and has been implicated in the pathophysiology of diabetic late complications. The regulation of SSAO production remains unknown. We studied correlations between plasma SSAO activity and parameters associated with diabetic late complications. METHODS: Plasma SSAO was measured in a well-characterised group of 287 patients with type 1 diabetes. Standard statistical methods were used to investigate correlations with clinical parameters and components of the renin-angiotensin system. RESULTS: Overall, plasma SSAO was elevated, at 693+/-196 mU/l (mean+/-SD; normal controls 352+/-102 mU/l). Plasma SSAO was higher in the group with late complications or hypertension, and in patients treated with ACE-inhibitors. In univariate analysis a significant positive correlation (p<0.001, r=0.27) was found between plasma SSAO and serum ACE activity in patients untreated with ACE inhibitors or angiotensin II receptor antagonists (n=221), but plasma SSAO did not differ by ACE I/D genotype. Plasma SSAO correlated positively with duration of diabetes, HbA(1)c and plasma renin, and negatively with plasma angiotensinogen and body mass index. A multiple regression analysis including these variables resulted in serum ACE activity (p<0.001), ACE genotype (negatively, p<0.001) and HbA(1)c (p=0.023) as explaining variables. CONCLUSIONS/INTERPRETATION: Results suggest that a common factor is involved in the regulation of both plasma SSAO and serum ACE, which is different from the genetic determination of ACE activity.

Amine Oxidase (Copper-Containing)↗
PubMed2005

Reproducibility and reliability of hypoglycaemic episodes recorded with Continuous Glucose Monitoring System (CGMS) in daily life.

AIM: Continuous glucose monitoring may reveal episodes of unrecognized hypoglycaemia. We evaluated reproducibility and reliability of hypoglycaemic episodes recorded in daily life by the Medtronic MiniMed Continuous Glucose Monitoring System (CGMS). METHODS: Twenty-nine adult patients with Type 1 diabetes underwent 6 days of continuous subcutaneous glucose monitoring, applying one CGMS on each side of the abdomen. Blood glucose was measured by HemoCue B-Glucose Analyzers six times daily and two different 4-point calibration sets were generated (set A and B). Using these calibration sets, CGMS raw data were recalibrated generating four different CGMS data sets [left-A (left side of abdomen, calibration set A), left-B, right-A and right-B]. Agreement between CGMS data sets was evaluated during hypoglycaemic events, comparing CGMS readings = 2.2 mmol/l with nadir values from corresponding CGMS data sets. CGMS readings were also compared with independent self-monitored blood glucose (SMBG) values. RESULTS: With hypoglycaemia (CGMS readings = 2.2 mmol/l) in calibration set left-A, values below 3.5 mmol/l were present in 99% (95% CI: 95-100%) of samples in left-B, 91% (95% CI: 84-96%) of samples in right-A, and 90% (95% CI: 83-95%) of samples in right B. In 84% of these episodes (95% CI: 59-96%) independent SMBG values were below 3.5 mmol/l. Difference in duration was observed with a median difference of 20 min; (left-A vs. right-B). CONCLUSION: Hypoglycaemic episodes recorded by CGMS are reproducible and agreement with independent SMBG values is acceptable for retrospective recording of hypoglycaemic events with CGMS.

Blood Glucose Self-Monitoring↗
PubMed2002

Prediction of severe hypoglycaemia by angiotensin-converting enzyme activity and genotype in type 1 diabetes.

AIMS/HYPOTHESIS: We have previously shown a strong relationship between high angiotensin-converting enzyme (ACE) activity, presence of the deletion (D) allele of the ACEgene and recall of severe hypoglycaemic events in patients with Type 1 diabetes. This study was carried out to assess this relationship prospectively. METHODS: We followed 171 adult outpatients with Type 1 diabetes in a one-year observational study with the recording of severe hypoglycaemia. Participants were characterised by serum ACE activity and ACE genotype and not treated with ACE inhibitors or angiotensin II receptor antagonists. RESULTS: There was a positive relationship between serum ACE activity and rate of severe hypoglycaemia with a 2.7 times higher rate in the fourth quartile of ACE activity compared to the first quartile (p=0.0007). A similar relationship was observed for the subset of episodes with coma (2.9 times higher rate in fourth quartile compared to first quartile; p=0.048). The impact of serum ACE activity was most pronounced in C-peptide negative subjects (4.2 times higher rate in fourth quartile compared to first quartile; p=0.003), and in this subgroup carriers of the D allele of the ACEgene had higher rates of severe hypoglycaemia compared to the group homozygous for the insertion (I) allele. In a multiple regression analysis high serum ACE activity and impaired awareness of hypoglycaemia were identified as the only significant predictors of severe hypoglycemia. CONCLUSION: High ACE activity and the presence of the D allele of the ACE gene predict a high rate of severe hypoglycaemia in Type 1 diabetes.

Adult↗
PubMed2001

Activity of angiotensin-converting enzyme and risk of severe hypoglycaemia in type 1 diabetes mellitus.

BACKGROUND: The insertion (I) allele of the angiotensin-converting-enzyme (ACE) gene occurs at increased frequency in endurance athletes. This association suggests that low ACE activity is favourable for performance in conditions with limited substrate availability. Such conditions occur in endurance athletes during competition and in diabetic patients during insulin-induced hypoglycaemia. Patients rely on preserved functional capacity to recognise hypoglycaemic episodes and avoid progression by self-treatment. We studied whether ACE activity is related to the risk of severe hypoglycaemia in type 1 diabetes. METHODS: Consecutive adult outpatients with type 1 diabetes, untreated with ACE inhibitors or angiotensin-II-receptor antagonists (n=207) reported their experience of mild and severe hypoglycaemia during the previous 1 year and 2 years. The patients were further characterised by diabetes history, degree of hypoglycaemia awareness, measurement of C-peptide, haemoglobin A(1c), and serum ACE concentrations, and determination of ACE genotype. FINDINGS: Patients with the DD genotype had a relative risk of severe hypoglycaemia in the preceding 2 years of 3.2 (95% CI 1.4-7.4) compared with those who had the II genotype. There was a significant relation between serum ACE activity and the rate of severe hypoglycaemia (relative risk per 10 U/L increment 1.4 [1.2-1.6]), corresponding to a 3.5 times higher risk for patients in the highest quartile than for those in the lowest quartile. Multiple regression analysis showed that the effect of the ACE genotype was explained by its influence on serum ACE activity and that the only other significant determinants of the risk of severe hypoglycaemia were the degree of hypoglycaemia awareness, b-cell function, and duration of diabetes of more than 20 years. INTERPRETATION: ACE activity is a clinically significant marker of the risk of severe hypoglycaemia in patients with type 1 diabetes, especially in those with impaired defence against hypoglycaemia. These findings need to be confirmed in prospective studies.

Adult↗
PubMed1999

Metabolic control and prevalence of microvascular complications in young Danish patients with Type 1 diabetes mellitus. Danish Study Group of Diabetes in Childhood.

AIMS: After Danish nationwide investigations (1987, 1989) demonstrated unacceptable blood glucose control in unselected young diabetic patients, we set out to estimate the present glycaemic control and the prevalence of microvascular complications in a cohort of children and adolescents participating in the two previous studies. METHODS: This follow-up represents 339 patients (47% of the inception cohort), median age 21.1 years (range 12.0-26.9), median diabetes duration 13.2 years (range 8.9-24.5). A standardized questionnaire, fundus photographs (with central reading) and a physical examination were performed. HbA1c and overnight albumin excretion rate (AER) were analysed centrally. RESULTS: Although 88% (n= 309) of the young persons were treated with three or more daily insulin injections, HbA1c (nondiabetic range 4.3-5.8, mean 5.3%) was 9.7+/-1.7% (mean+/-SD). Males had higher HbA1c values than females (P < 0.015). Mean daily insulin dose was 0.92+/-0.25 IU.kg(-1).24h(-1). Microalbuminuria (AER > 20-150 microg/min) and macroalbuminuria (AER > 150 microg/min) were found in 9.0% and 3.7% of the patients, respectively, and was associated with increased diastolic blood pressure (P<0.01) and presence of retinopathy (P<0.01). Retinopathy was present in approximately 60% of the patients and was associated with age, diabetes duration, HbA1c, diastolic blood pressure and AER (all P<0.01). Subclinical neuropathy (vibration perception threshold by biothesiometry > 6.5 V) was found in 62% and showed a significant association with age, linear height, diastolic blood pressure (all P < 0.01) and diabetic retinopathy (P = 0.01). CONCLUSIONS: In spite of the majority of the patients being on multiple insulin injections, only 11% had HbA1c values below 8% and the prevalence of diabetic microvascular complications in kidneys, eyes and nerves was unacceptable high.

Adolescent↗
PubMed1997

Renal threshold for glucose in non-insulin-dependent diabetic patients.

Measurement of glycosuria is still widely used for home monitoring of glycaemia control in non-insulin-dependent diabetes (NIDDM). This method has been criticized because the renal threshold for glucose (RTglu) varies between subjects. In order to evaluate the validity of RTglu by measuring corresponding measurements of blood and urine glucose in NIDDM patients, we studied the blood/urine glucose relationship in 24 NIDDM patients. RTglu estimated from 75 contemporary blood and urine glucose concentrations measured at home by each patient (h-RTglu) was compared with RTglu measured by a hyperglycaemic glucose clamp (c-RTglu). H-RTglu and c-RTglu, being 7.6 mmol/1 (range 5.5-12.4) and 10.3 mmol/1 (6.2-12.3) respectively (P < 0.005), were weakly correlated (R(S) = 0.35, P = 0.15). In conclusion, c-RTglu varies two-fold between NIDDM patients. RTglu detected by home monitored urine and blood glucose determinations underestimates the true RTglu, probably due to the splay phenomenon. However, the method for detection of RTglu used by us seems of clinical relevance, since it reflects the individual blood glucose level at which glucose is detectable in the urine.

Aged↗
PubMed1996

[Glucose tolerance in patients with cystic fibrosis].

In order to define prevalence and incidence of diabetes mellitus in cystic fibrosis, we followed 191 unselected patients above two years of age (median 13.6) in a five-year prospective study with annual oral glucose tolerance tests. The prevalence of diabetes increased from 11 to 24% during the study period with an annual age-dependent incidence rate of 4-9%. Diabetes was diagnosed at a median age of 21 years (range 3-40). At diagnosis of diabetes, hyperglycaemia, fasting hyperglycaemia (> or = 7.8 mmol/l), and increased haemoglobin Alc levels (> 6.4) were present in 33%, 16% and 16% of the diabetic patients, respectively. Impaired glucose tolerance implied a higher risk than normal glucose tolerance for the development of diabetes (odds ratio 5.6). In 58% of cases with impaired glucose tolerance, however, glucose tolerance was normalised at the next annual test. Normal glucose tolerance was found in only 37% of the patients at all five tests. Within this group of patients, median fasting and two-hour post-load plasma glucose concentrations and haemoglobin Alc levels increased by 6-8% during five years. Thus, the prevalence and incidence of diabetes in patients with cystic fibrosis is very high and increases with age. Since symptoms of hyperglycaemia and increased fasting plasma glucose and haemoglobin Alc levels are inconstant findings in newly diagnosed diabetic cystic fibrosis patients, we recommend annual oral glucose tolerance tests in all cystic fibrosis patients above the age of 10 years.

Adolescent↗
PubMed1996

[Pituitary function in hemochromatosis].

A review of the literature on pituitary function in haemochromatosis is presented. In morphological studies pituitary iron deposition, in particular in gonadotropic cells, has been demonstrated. In a number of case series, insufficiency of pituitary gonadotropic secretion with clinical hypogonadism was observed in 46% of the patients. Overt insufficiency of the other hormonal axes was infrequent. However, subclinical insufficiency of the growth hormone axis was present in 15%, of the lactotropic axis in 8%, of the thyroid axis in 4% and of the adrenocortical axis in 1.5% of the patients. Lactotropic, thyroid or adrenocortical insufficiency was usually associated with hypogonadism or growth hormone insufficiency. Investigation of pituitary function (in first line the gonadotropic and the somatotropic function) in patients with primary or secondary haemochromatosis is recommended on wide indications, in order to initiate relevant substitution therapy.

Hemochromatosis↗
PubMed1995

Glucose tolerance in patients with cystic fibrosis: five year prospective study.

OBJECTIVES: To study prevalence and incidence of diabetes mellitus in patients with cystic fibrosis. DESIGN: Five year prospective study with annual oral glucose tolerance tests. SETTING: CF Center Copenhagen, Denmark. SUBJECTS: 191 patients with cystic fibrosis aged above 2 years. MAIN OUTCOME MEASURES: Glucose tolerance, plasma glucose concentrations after fasting and after glucose loading, and haemoglobin A1c levels. RESULTS: Prevalence of diabetes increased from 11% (n = 21) to 24% (n = 46) during study, with annual age dependent incidence of 4-9%. Diabetes was diagnosed at median age of 21 (range 3-40). At diagnosis of diabetes, symptoms of hyperglycaemia were present in 33% of patients, fasting hyperglycaemia (> or = 7.8 mmol/l) was seen in 16%, and increased haemoglobin A1c levels (> 6.4%) were seen in 16%. Impaired glucose tolerance implied higher risk for development of diabetes than normal glucose tolerance (odds ratio 5.6). In 58% of cases with impaired glucose tolerance, however, glucose tolerance was normal at next annual test. Normal glucose tolerance was found in only 37% of patients at all five tests. Within this group of patients, median plasma glucose concentrations after fasting and after glucose loading and haemoglobin A1c levels increased by 6-8% during study. CONCLUSIONS: Prevalence and incidence of diabetes in cystic fibrosis patients was high and increased with age. Since hyperglycaemic symptoms, fasting hyperglycaemia, and increased levels of glycated haemoglobin did not reliably identify diabetes mellitus, we recommend annual oral glucose tolerance tests in all cystic fibrosis patients aged over 10 years.

Adolescent↗
PubMed1994

Insulin sensitivity and insulin clearance in cystic fibrosis patients with normal and diabetic glucose tolerance.

OBJECTIVE: We studied glucose metabolism and insulin kinetics in cystic fibrosis patients with diabetic and normal glucose tolerance. DESIGN: Measurements of blood glucose and serum free insulin concentrations during hyperinsulinaemic normoglycaemic clamp and post-clamp insulin decay, followed by the calculation of insulin sensitivity (M-value and M/I ratio), insulin clearance rate, serum half-life and apparent distribution space for insulin. SUBJECTS: Cystic fibrosis patients, age range 20-29 years, with diabetes mellitus (n = 10) and normal glucose tolerance (n = 10), and 10 age-matched control subjects. RESULTS: During the glucose clamp, diabetic cystic fibrosis patients needed less glucose than cystic fibrosis patients with normal glucose tolerance and control subjects (M-value), and steady-state serum insulin concentrations were lower in cystic fibrosis patients with diabetic and normal glucose tolerance than in control subjects. The quantity of glucose metabolized per unit of serum insulin concentration (M/I ratio) was similar in the three study groups (median approximately 145 (mumol/kg/min)/(nmol/l); range 70-252). Insulin clearance rates were higher in cystic fibrosis patients with diabetic (24.4 (19.3-29.9) ml/kg/min) and normal (22.6 (14.9-28.4) ml/kg/min) glucose tolerance than in control subjects (17.5 (15.9-24.2) ml/kg/min). Although insulin clearance rates were inversely related to body mass index (R(S) = -0.59, P < 0.001), the higher insulin clearance rates in CF patients cannot be accounted for solely by differences in body mass index since the insulin clearance rates were similarly increased in patients with body mass index above and below 20 kg/m2 (22.7 (14.9-28.4) and 24.4 (19.3-29.9) ml/kg/min, respectively). Serum half-lives for insulin were shorter in cystic fibrosis patients (approximately 4.3 (3.2-7.2) min) than in control subjects (5.9 (3.8-12.5) min), whereas the apparent distribution spaces for insulin were similar in the three study groups (approximately 150 (88-391) ml/kg). CONCLUSIONS: Insulin sensitivity, calculated as the quantity of glucose metabolized per kg body weight per unit of serum insulin concentration, is normal in cystic fibrosis patients with normal glucose tolerance and with well controlled diabetes mellitus. The insulin clearance rate is increased in cystic fibrosis patients with diabetic and normal glucose tolerance, owing to a shorter serum half-life of insulin, whereas the apparent distribution space for insulin is normal.

Adult↗
PubMed1994

Diabetes mellitus in Danish cystic fibrosis patients: prevalence and late diabetic complications.

The prevalences of impaired glucose tolerance (IGT), diabetes mellitus and late diabetic complications were studied in all Danish cystic fibrosis (CF) patients. A total of 311 CF patients were identified with an estimated ascertainment rate above 98%. Glucose tolerance was classified in 278 (89%) patients: the prevalences of IGT and diabetes mellitus were 13.7% (38 patients) and 14.7% (41 patients), respectively, with no sex differences. The prevalence of diabetes mellitus increased with age but not with the severity of CF as compared with age- and sex-matched non-diabetic CF patients. Diabetes was diagnosed at a median age of 20 years (range 3-40 years) and the duration of diabetes was 1.7 years (0.1-17 years). Twenty-eight of the diabetic patients (70%) were treated with insulin, on average 20 (4-90) IU per day. Late diabetic complications were identified in 4 patients (10%) with a duration of diabetes mellitus of 1-17 years: background retinopathy (2 patients), diabetic nephropathy (1 patient), microalbuminuria (1 patient) and neuropathy (2 patients). Thus diabetic CF patients are probably not less prone to develop late diabetic complications than patients with other types of diabetes of equally long duration and comparable glycemic control.

Adolescent↗
PubMed1994

Diabetes mellitus in cystic fibrosis: effect of insulin therapy on lung function and infections.

The effect of insulin therapy on lung function and lung infections was studied in a retrospective case-control design in 18 diabetic cystic fibrosis (CF) patients; 18 non-diabetic CF patients, matched for sex, age and presence of chronic Pseudomonas aeruginosa lung infection, served as controls. Parameters of CF clinical status were collected for six years before and two years after the onset of insulin therapy in the diabetic patients. Before onset of insulin therapy, body mass index (BMI) and forced vital capacity (FVC) in (pre)diabetic patients deviated increasingly from those in control patients. Decreases in BMI and lung function during the past three months before onset of insulin therapy were reverted within three months of insulin therapy. From three months to two years after onset of insulin therapy, differences in BMI and lung function diminished between diabetic and control patients. After two years of insulin therapy, BMI was similar in diabetic and non-diabetic patients and the percentage differences in forced expiratory volume in 1s (FEV1) and FVC between the two groups were similar to those found six years before the onset of insulin therapy. The finding that insulin therapy improves lung function in diabetic CF patients suggests strongly that the insidious decline in lung function seen during the years before the diagnosis of diabetes mellitus results from the pre-diabetic condition. After onset of insulin therapy, the percentages of sputum examinations positive for Haemophilus influenzae and Streptococcus pneumoniae decreased in the diabetic patients, whereas parameters of lung infections with P. aeruginosa and Staphylococcus aureus remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Diabetes mellitus in cystic fibrosis: genetic and immunological markers.

Family history, as well as genetic and immunological markers of diabetes mellitus, were studied in cystic fibrosis (CF) patients with and without diabetes mellitus. Positive family history of diabetes mellitus in first-degree relatives was found in only 6 of 210 (3%) CF patients, with no difference between non-diabetic and diabetic patients. The frequency distributions of the HLA types DR3, DR4 and DR3/4, which normally confer susceptibility to insulin-dependent diabetes mellitus and of HLA-DR2, which normally confers resistance to insulin-dependent diabetes mellitus, were not different in non-diabetic CF patients, diabetic CF patients and normal subjects. The genotypic frequencies of tumor necrosis factor-beta and of heat shock protein 70, located within the HLA region on chromosome 6, in CF patients with diabetes were not different from those in patients with insulin-dependent diabetes mellitus, while non-diabetic CF patients and normal subjects shared other patterns. The frequencies of the interleukin-1 beta alleles, located on chromosome 2, were not different in non-diabetic and diabetic CF patients, insulin-dependent diabetic patients and normal subjects. Islet cell cytoplasmic antibodies, measured before, at and after the diagnosis of diabetes in 33 diabetic CF patients and in 32 matched non-diabetic CF patients, were detected in only 2 of 236 (0.8%) serum samples: in a pre-diabetic patient and in a non-diabetic control patient. Birth weights were not different in diabetic and non-diabetic CF patients, arguing against the importance of the intrauterine environment as a determinant in the transmission of diabetes mellitus in CF patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗