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Biomedical subjects

Timothy W Jones

Publications and source records attributed to Timothy W Jones.

At least 19 recordsLinked to original sources
PubMed2006

Glucose requirements to maintain euglycemia after moderate-intensity afternoon exercise in adolescents with type 1 diabetes are increased in a biphasic manner.

CONTEXT: Exercise increases the risk of hypoglycemia in type 1 diabetes. OBJECTIVE: This study aimed to investigate how the amount of glucose required to prevent an exercise-mediated fall in glucose level changes over time in adolescents with type 1 diabetes. SETTING: The study took place at a tertiary pediatric referral center. DESIGN, PARTICIPANTS, AND INTERVENTION: Nine adolescents with type 1 diabetes mellitus (five males, four females, aged 16 +/- 1.8 yr, diabetes duration 8.2 +/- 4.1 yr, hemoglobin A1c 7.8 +/- 0.8%, mean +/- SD) were subjected on two different occasions to a rest or 45 min of exercise at 95% of their lactate threshold. Insulin was administered iv at a rate based on their usual insulin dose, with similar plasma insulin levels for both studies (82.1 +/- 19.0, exercise vs. 82.7 +/- 16.4 pmol/liter, rest). Glucose was infused to maintain euglycemia for 18 h. MAIN OUTCOME MEASURES: Glucose infusion rates required to maintain euglcycemia and levels of counterregulatory hormones were compared between rest and exercise study nights. RESULTS: Glucose infusion rates to maintain stable glucose levels were elevated during and shortly after exercise, compared with the rest study, and again from 7-11 h after exercise. Counterregulatory hormone levels were similar between exercise and rest studies except for peaks in the immediate postexercise period (epinephrine, norepinephrine, GH, and cortisol peaks: 375.6 +/- 146.9 pmol/liter, 5.59 +/- 0.73 nmol/liter, 71.9 +/- 14.8 mIU/liter, and 558 +/- 69 nmol/liter, respectively). CONCLUSIONS: The biphasic increase in glucose requirements to maintain euglycemia after exercise suggests a unique pattern of early and delayed risk for nocturnal hypoglycemia after afternoon exercise.

Adolescent↗
PubMed2006

Increasing body mass index z-score is continuously associated with complications of overweight in children, even in the healthy weight range.

CONTEXT: Overweight/obesity in children is increasing. Incidence data for medical complications use arbitrary cutoff values for categories of overweight and obesity. Continuous relationships are seldom reported. OBJECTIVES: The objective of this study is to report relationships of child body mass index (BMI) z-score as a continuous variable with the medical complications of overweight. DESIGN: This study is a part of the larger, prospective cohort Growth and Development Study. SETTING: Children were recruited from the community through randomly selected primary schools. Overweight children seeking treatment were recruited through tertiary centers. PARTICIPANTS: Children aged 6-13 yr were community-recruited normal weight (n = 73), community-recruited overweight (n = 53), and overweight treatment-seeking (n = 51). Medical history, family history, and symptoms of complications of overweight were collected by interview, and physical examination was performed. Investigations included oral glucose tolerance tests, fasting lipids, and liver function tests. MAIN OUTCOME MEASURE: Adjusted regression was used to model each complication of obesity with age- and sex-specific child BMI z-scores entered as a continuous dependent variable. RESULTS: Adjusted logistic regression showed the proportion of children with musculoskeletal pain, obstructive sleep apnea symptoms, headaches, depression, anxiety, bullying, and acanthosis nigricans increased with child BMI z-score. Adjusted linear regression showed BMI z-score was significantly related to systolic and diastolic blood pressure, insulin during oral glucose tolerance test, total cholesterol, high-density lipoprotein, triglycerides, and alanine aminotransferase. CONCLUSION: Child's BMI z-score is independently related to complications of overweight and obesity in a linear or curvilinear fashion. Children's risks of most complications increase across the entire range of BMI values and are not defined by thresholds.

Adolescent↗
PubMed2006

Effects of hypoglycemia on human brain activation measured with fMRI.

Functional magnetic resonance imaging (fMRI) was used to measure the effects of acute hypoglycemia caused by passive sensory stimulation on brain activation. Visual stimulation was used to generate blood-oxygen-level-dependent (BOLD) contrast, which was monitored during hyperinsulinemic hypoglycemic and euglycemic clamp studies. Hypoglycemia (50 +/- 1 mg glucose/dl) decreased the fMRI signal relative to euglycemia in 10 healthy human subjects: the fractional signal change was reduced by 28 +/- 12% (P < .05). These changes were reversed when euglycemia was restored. These data provide a basis of comparison for studies that quantify hypoglycemia-related changes in fMRI activity during cognitive tasks based on visual stimuli and demonstrate that variations in blood glucose levels may modulate BOLD signals in the healthy brain.

Adult↗
PubMed2006

Independent effects of socioeconomic status and place of residence on the incidence of childhood type 1 diabetes in Western Australia.

OBJECTIVE: To analyze the incidence of type 1 diabetes in 0- to 14-year olds in Western Australia, from 1985 to 2002, by region and socioeconomic status. METHODS: Primary case ascertainment was from the prospective population-based Western Australian Diabetes Register, and secondary case ascertainment was from the Western Australian Hospital Morbidity Data System. The address at diagnosis was used to categorize cases into urban, rural and remote areas and into five socioeconomic groups using the Index of Relative Socioeconomic Disadvantage. Denominator data were obtained from the Australian Bureau of Statistics. Poisson regression was used to analyze the incidence rates by area and socioeconomic status. RESULTS: There were a total of 1143 cases (904 urban, 190 rural and 49 remote). Case ascertainment was estimated to be 99.8% complete. The mean annual age-standardized incidence from 1985 to 2002 was 18.1 per 100,000 person years in urban (95% CI: 16.3-19.9), 14.3 per 100,000 in rural (95% CI: 11.4-7.3) and 8.0 per 100,000 in remote areas (95% CI: 5.8-10.3). The incidence was significantly higher in urban compared with rural (rate ratio 1.27, p = 0.001) and remote (rate ratio 2.28, p < 0.001) areas. The incidence increased with higher socioeconomic status. The incidence in the highest socioeconomic group was 56% greater than the lowest socioeconomic group (rate ratio 1.56, p < 0.001). These differences in incidence by socioeconomic status and region were independent of each other. CONCLUSIONS: Higher socioeconomic status and residence in the urban area are independently associated with an increased risk of childhood type 1 diabetes in Western Australia.

Adolescent↗
PubMed2006

Type 2 diabetes in youth from the Western Pacific region: glycaemic control, diabetes care and complications.

OBJECTIVE: To describe the glycaemic control, diabetes care and prevalence of complications in youth with type 2 diabetes from the Western Pacific Region. RESEARCH DESIGN AND METHODS: Cross-sectional, clinic-based audit of 331 patients aged < 18 years from 56 centres in Australia, China-Beijing, China-Shanghai, China-Hong Kong, Indonesia, Japan, South Korea, Malaysia, Philippines, Singapore, Taiwan and Thailand. Clinical and management data were recorded along with glycated haemoglobin (HbA(1c)), lipids and complication rates. MAIN OUTCOME MEASURES: Glycaemic control, complications, diabetes management. RESULTS: Median age was 14.9 years (interquartile range 13.2-16.4 years) and median diabetes duration 2.3 years (1.4-3.6 years). Median HbA(1c) was 7% (5.9-9.9%) and HbA(1c) was > 7.5% in 40% of patients. In multiple regression analysis, glycaemic control varied significantly between countries (p = 0.02); higher HbA(1c) was associated with fewer home blood glucose measurements (p = 0.005) and higher insulin dose/kg (p < 0.0001). Blood glucose monitoring was performed by 65% of patients (range 33-96% by country). In 25% of patients, management consisted of diet alone or no treatment (range 0-53% by country); oral anti-diabetic drugs alone were used in 49%, insulin alone in 11% and both in 15%. Microalbuminuria was found in 8% and hypertension in 24%. The risk of hypertension increased with higher BMI (OR 1.16, 95% CI 1.09-1.24, p < 0.0001); antihypertensive agents were used in 4% of patients. CONCLUSIONS: The management of type 2 diabetes in youth from the Western Pacific Region varies widely. Hypertension and microalbuminuria were frequent, but not commonly treated. Further investigation into the natural history and risk factors for complications in youth with type 2 diabetes is required to assist in developing evidence based management guidelines.

Adolescent↗
PubMed2006

Do skinfolds accurately assess changes in body fat in obese children and adolescents?

PURPOSE: Obesity is epidemic in Western societies, with rapid rates of increase in the young. Various methods exist for the assessment of body composition, but these have not been compared in obese children and adolescents. This study compared methods of body composition assessment in obese young people to determine whether changes in various measures of body composition as a result of exercise training were correlated. METHODS: Multiple anthropometric measures (weight, height, body mass index (BMI), skinfolds, waist and hip girths) and dual-energy x-ray absorptiometry (DEXA) were undertaken in 38 obese children and adolescents (12.7 +/- 2.1 yr) at baseline and following 8 wk of exercise training. RESULTS: At baseline, there were strong relationships (all P < 0.01) between DEXA total fat and weight (r = 0.83), BMI (r = 0.86), waist girth (r = 0.81), hip girth (r = 0.88), sum of six skinfolds (sum6, r = 0.79), and percent body fat (percent body fat) calculated using a four-skinfold equation (EQ4; r = 0.69). Similar relationships (all P < 0.001) existed between DEXA abdominal fat and weight (r = 0.79), waist girth (r = 0.83), hip girth (r = 0.69), and height (r = 0.71). Neither skinfold sums, nor percent body fat calculated from skinfold equations, were selected as independent predictors of DEXA total or abdominal fat by stepwise hierarchical linear regression. The reductions in DEXA total and abdominal fat following exercise were not predicted by changes in skinfolds or percent body fat calculated from skinfolds. CONCLUSION: These data suggest that body fat derived from skinfold measures is poorly predictive of abdominal and total fat derived from DEXA in obese children and adolescents. This finding highlights the limitations of skinfolds in obese subjects and questions the validity of their use to assess changes in body composition with interventions such as exercise training.

Adolescent↗
PubMed2006

Acute effects of hyperglycaemia in children with type 1 diabetes mellitus: the patient's perspective.

INTRODUCTION: This study presents the results of a systematic examination of how parents and patients perceive the effects of acute hyperglycaemia on mood and on intellectual and fine-motor performance. METHODS: A random sample of parents and children with type 1 diabetes mellitus (n = 380) were asked via questionnaire about their perception of the effects of hyperglycaemia. RESULTS: Answers were received from 368 children and parents (97%); mean age was 12.5 years (range 3.7 to 19.8 years). Blood glucose levels between 15-18 mmol/l were reported by 68% to affect thinking performance, by 75% to affect mood and emotions and by 53% to affect coordination. The symptoms most commonly associated with hyperglycaemia were (in decreasing order): irritable (64%), short-tempered (60%), moody (56%), unreasonable (43%), aggressive (37%), hyperactive (31%), sad/depressed (27%) confused (23%), clumsy (18%). Homework was thought to be affected by hyperglycaemia in 36%, sport in 25%, play activity in 32%. Higher mean HbA1c since diagnosis was associated with higher reporting of effects on feeling/mood (p <0.001). Parents were especially concerned about the effects of hyperglycaemia on school and social interaction. CONCLUSIONS: The effects of hyperglycaemia on immediate performance are of concern to children and parents. Hyperglycaemia (15-18 mmol/l) is reported to influence emotion and behaviour more than intellectual and fine-motor performance. This may contribute to the adverse psychological consequences of type 1 diabetes mellitus in children.

Adolescent↗
PubMed2006

The 10-s maximal sprint: a novel approach to counter an exercise-mediated fall in glycemia in individuals with type 1 diabetes.

OBJECTIVE: To investigate whether a short maximal sprint can provide another means to counter the rapid fall in glycemia associated with moderate-intensity exercise in individuals with type 1 diabetes and therefore decrease the risk of early postexercise hypoglycemia. RESEARCH DESIGN AND METHODS: In the study, seven male subjects with type 1 diabetes injected their normal insulin dose and ate their usual breakfast. When their postprandial glycemia fell to approximately 11 mmol/l, they pedaled at 40% Vo(2peak) for 20 min on a cycle ergometer then immediately engaged in a maximal 10-s cycling sprint (sprint trial) or rested (control trial); the sprint and rest trials were administered in a counterbalanced order. RESULTS: Moderate-intensity exercise resulted in a significant fall (P < 0.05) in glycemia in both trials (means +/- SE: 3.6 +/- 0.5 vs. 3.1 +/- 0.5 mmol/l for sprint and control, respectively). The subsequent short cycling sprint opposed a further fall in glycemia for 120 min, whereas in the absence of a sprint, glycemia decreased further (3.6 +/- 1.22 mmol/l; P < 0.05) after exercise. The stabilization of glycemia in the sprint trial was associated with elevated levels of catecholamines, growth hormone, and cortisol. In contrast, these hormones remained at stable or near-stable levels in the control trial. Changes in insulin and free fatty acid levels were similar in the sprint and control trials. CONCLUSIONS: These results suggest that after moderate-intensity exercise, it is preferable for young individuals with insulin-treated, complication-free type 1 diabetes to engage in a 10-s maximal sprint to acutely oppose a further fall in glycemia than to only rest. The addition of the sprint after moderate-intensity exercise provides another means to reduce the risk of hypoglycemia in active individuals with type 1 diabetes.

Adolescent↗
PubMed2005

Point-of-care testing of HbA1c and blood glucose in a remote Aboriginal Australian community.

OBJECTIVES: To assess the accuracy of point-of-care (POC) measurements of capillary blood glucose and glycosylated haemoglobin (HbA(1c)) levels in a remote Aboriginal community with high diabetes prevalence. DESIGN: Cross-sectional study comparing POC capillary glucose and HbA(1c) results with those from corresponding venous samples measured in a reference laboratory. PARTICIPANTS AND SETTING: 152 residents aged 11-76 years (representing 76% of population aged over 11 years) had POC glucose measurement in November 2003; 88 with POC glucose level > or = 5.0 mmol/L, or self-reported diabetes, had POC HbA(1c) and laboratory glucose and HbA(1c) measurements. MAIN OUTCOME MEASURES: POC fasting capillary levels of glucose (HemoCue Glucose 201 analyser, Medipac Scientific, Sydney) and HbA(1c) (DCA 2000+ analyser, Bayer Australia, Melbourne); correlation and mean difference between capillary POC and venous blood laboratory measurements of glucose and HbA(1c). RESULTS: Mean and median POC capillary glucose levels were 7.99 mmol/L and 6.25 mmol/L, respectively, while mean and median laboratory venous plasma glucose concentrations were 7.63 mmol/L and 5.35 mmol/L. Values for POC capillary HbA(1c) and laboratory HbA(1c) were identical: mean, 7.06%; and median, 6.0%. The correlation coefficient r for POC and laboratory results was 0.98 for glucose and 0.99 for HbA(1c). The mean difference in results was 0.36 mmol/L for glucose (95% CI, 0.13-0.62; limits of agreement [LOA], - 2.07 to 2.79 mmol/L; P = 0.007) and < 0.01% for HbA(1c) (95% CI, - 0.07% to 0.07%; LOA, - 0.66% to 0.66%; P = 0.95), respectively. CONCLUSIONS: POC capillary HbA(1c) testing, in particular, offers an accurate, practical, community-friendly way of monitoring diabetes in rural and remote clinical settings. POC capillary glucose results should be confirmed by a laboratory test of venous plasma if the results are likely to significantly influence clinical decisions.

Adolescent↗
PubMed2005

Cognitive functioning in children with early onset type 1 diabetes and severe hypoglycemia.

OBJECTIVE: To investigate whether severe hypoglycemia in young children with early-onset type 1 diabetes (T1DM) is associated with subsequent abnormalities in cognitive status. STUDY DESIGN: Recruitment was from a large population-based database of children and adolescents with T1DM. Children and adolescents with early-onset T1DM (<6 years) were eligible for the study. Diabetic individuals (n = 41) with a prospectively documented history of seizure or coma were compared with peers with no history of severe hypoglycemic events (n = 43). A comprehensive test battery of learning and memory was used together with intellectual and behavioral measures. RESULTS: No significant group differences were revealed on the intellectual, memory, or behavioral measures. Similarly, those participants with a history of early first seizure did not differ from their peers with no seizures. There were no significant group differences on the memory subtests that were examined given their potential sensitivity to compromised hippocampal function. CONCLUSIONS: There was no clear evidence from this cohort that episodes of seizure or coma, even those occurring in very early childhood, resulted in broad cognitive dysfunction, nor was there evidence of specific memory difficulties at the time of testing in children and adolescents with early-onset T1DM.

Age of Onset↗
PubMed2005

Exercise training in obese children and adolescents: current concepts.

Childhood obesity has reached epidemic proportions worldwide and is associated with increased cardiovascular mortality and morbidity in adult life. The increase in fat mass in children and adolescents has occurred concomitantly with a decline in reported time for exercise. Evidence suggests that non-physically active children are more likely to become non-physically active adults and that encouraging the development of physical activity habits in children helps establish patterns that continue into adulthood. Dietary treatment of obesity is relatively ineffective in adults and it has been suggested that prevention of obesity in childhood and adolescence should emphasise increased physical activity rather than diet because of fears relating to the adverse effects of inappropriate eating patterns. Despite this, there are very few randomised controlled studies investigating the efficacy of exercise training in obese children or adolescents and many of the extant studies have been poorly controlled and have not specifically stratified the independent effect of exercise versus dietary modification. This review focuses on the well designed controlled trials that have evaluated the effect of exercise training in obese children and adolescents on body composition, haemodynamic and metabolic variables, cardiovascular fitness, muscular strength and vascular function. These studies indicate that, although exercise training does not consistently decrease bodyweight or body mass index, it is associated with beneficial changes in fat and lean body mass, emphasising the importance of comprehensive assessment of body composition in future exercise-training studies. Exercise training improves cardiovascular fitness and muscular strength; however, it seems to have little effect on blood lipid profile or blood pressure in obese young people. Importantly, recent studies have demonstrated that exercise training improves vascular endothelial function, an important surrogate measure that may predict future atherosclerotic risk in obese children and adolescents. Given that improvement in vascular function in these training studies occurred in the absence of changes in lipid fractions, haemodynamic variables or glucose metabolism, exercise appears to have a direct beneficial effect on the vasculature, in addition to its putative benefits through risk-factor modification.

Adolescent↗
PubMed2005

The decline in blood glucose levels is less with intermittent high-intensity compared with moderate exercise in individuals with type 1 diabetes.

OBJECTIVE: To compare the response of blood glucose levels to intermittent high-intensity exercise (IHE) and moderate-intensity exercise (MOD) in individuals with type 1 diabetes. RESEARCH DESIGN AND METHODS: Seven healthy individuals with type 1 diabetes were tested on two separate occasions, during which either a 30-min MOD or IHE protocol was performed. MOD consisted of continuous exercise at 40% Vo(2peak), while the IHE protocol involved a combination of continuous exercise at 40% Vo(2peak) interspersed with 4-s sprints performed every 2 min to simulate the activity patterns of team sports. RESULTS: Both exercise protocols resulted in a decline in blood glucose levels. However, the decline was greater with MOD (-4.4 +/- 1.2 mmol/l) compared with IHE (-2.9 +/- 0.8 mmol/l; P < 0.05), despite the performance of a greater amount of total work with IHE (P < 0.05). During 60 min of recovery from exercise, glucose levels remained higher in IHE compared with MOD (P < 0.05). Furthermore, glucose levels remained stable during recovery from IHE, while they continued to decrease after MOD (P < 0.05). The stabilization of blood glucose levels with IHE was associated with elevated levels of lactate, catecholamines, and growth hormone during early recovery from exercise (P < 0.05). There were no differences in free insulin, glucagon, cortisol, or free fatty acids between MOD and IHE. CONCLUSIONS: The decline in blood glucose levels is less with IHE compared with MOD during both exercise and recovery in individuals with type 1 diabetes.

Adult↗
PubMed2004

Exercise training normalizes vascular dysfunction and improves central adiposity in obese adolescents.

OBJECTIVES: We sought to characterize the impact of obesity on vascular function in adolescents and to determine whether an exercise program reverses abnormalities in endothelial function. BACKGROUND: Obesity, a major modifiable risk factor for cardiovascular disease, is epidemic in Western societies, with rapid rates of increase in the young. Atherosclerosis begins in childhood, and endothelial dysfunction is its earliest detectable manifestation. METHODS: The influence of eight weeks of circuit training (CT) was examined in 19 obese subjects (14.3 +/- 1.5 years), using a randomized, crossover protocol. Functional capacity and muscular strength were assessed by standard techniques. Body composition was examined using anthropometric measures and dual-energy X-ray absorptiometry. Conduit vessel endothelial function was assessed using high-resolution ultrasound and flow-mediated dilation (FMD) of the brachial artery. RESULTS: Circuit training decreased abdominal and trunk fat and significantly improved fitness and muscular strength (p < 0.05). In the obese group, FMD was significantly impaired relative to control subjects (n = 20) at entry (5.3 +/- 0.9% vs. 8.9 +/- 1.5%, p < 0.05) and was normalized after CT (8.8 +/- 0.8%, p < 0.05). CONCLUSIONS: Circuit training improved functional capacity, muscular strength, and body composition in obese adolescents. Furthermore, conduit vessel function was normalized after exercise training. If vascular dysfunction is an integral component of the pathogenesis of vascular disease, this study supports the value of an exercise program in the management of obese adolescents.

Adipose Tissue↗
PubMed2004

Increase in type 2 diabetes in children and adolescents in Western Australia.

OBJECTIVES: To document diagnosis rates of type 2 diabetes mellitus in children and adolescents in Western Australia over the past 12 years, the clinical characteristics of these patients and any comorbidities. DESIGN: Review of a prospectively recorded diabetes database. SETTING: Tertiary paediatric referral centre (the only such centre in WA). PATIENTS: All children and adolescents aged < 17 years diagnosed with type 2 diabetes between 1990 and 2002 and managed by Princess Margaret Hospital Diabetes Unit. MAIN OUTCOME MEASURES: Anthropometric and demographic data; glycohaemoglobin (HbA(1c)) level; blood pressure; lipid levels; presence of acanthosis nigricans. RESULTS: 43 patients (15 males and 28 females) were diagnosed with type 2 diabetes. Age (SD) at diagnosis was 13.6 (1.8) years. The rate of diagnosis has been progressively increasing (average annual increase in the unadjusted overall rates of type 2 diabetes was 27%). Twenty-three patients (53%) were of Indigenous origin and 18 (42%) resided in rural areas. The mean (SD) HbA(1c) level at diagnosis was 10.0% (3.2%). Seventy-two per cent of patients had acanthosis nigricans, 59% had hypertension, and 24% had hyperlipidaemia. CONCLUSIONS: There has been an increase in the diagnosis rate of type 2 diabetes in children and adolescents in WA. Comorbidities are frequent.

Acanthosis Nigricans↗
PubMed2004

Effects of exercise training on vascular function in obese children.

OBJECTIVES: Atherosclerosis is a disease that begins in childhood; endothelial dysfunction is its earliest detectable manifestation, and primary prevention strategies are likely to be most effective if instituted early. The aim of this study was to characterize the impact of obesity on vascular function in young children and to determine whether an exercise program improves abnormalities in vascular function. STUDY DESIGN: The influence of 8 weeks of exercise training was examined in 14 obese subjects, 8.9 +/- 0.4 years of age, with the use of a randomized crossover protocol. Conduit vessel endothelial function was assessed by means of high-resolution ultrasound and flow-mediated dilation of the brachial artery (FMD). RESULTS: Exercise training did not change subcutaneous fat mass, body weight, or body mass index. FMD in the obese group was significantly impaired relative to matched control subjects at entry (6.00% +/- 0.69% to 12.32% +/- 3.14%, P <.0001). FMD significantly improved with exercise training (7.35% +/- 0.99%, P <.05) in the obese group. CONCLUSIONS: Conduit vessel FMD, a validated surrogate measure of early atherosclerosis, was impaired in obese children but improved as a result of exercise training. This study supports the value of an exercise program in the treatment of obese children in a primary prevention setting.

Analysis of Variance↗
PubMed2004

Lack of effect of oral glucose loading on conduit vessel endothelial function in healthy subjects.

The aim of the present study was to investigate the impact of an oral glucose load on circulating insulin and glucose levels and arterial function in healthy non-diabetic subjects. Thirty-nine non-obese, healthy subjects (24 female, 15 male), aged 21.0+/-1.8 years of age, were randomly assigned to undergo either an OGTT (oral glucose tolerance test; 75 g of glucose) or administration of a placebo. Analyses of lipids, liver function and HbA(1c) (glycated haemoglobin) at baseline revealed results which were within the standard reference range. Insulin and glucose levels as well as vascular function [FMD (flow-mediated dilation)] were measured at 0, 60 and 120 min. Compared with baseline, the control subjects did not exhibit any significant changes in glucose or insulin levels, whereas, in the OGTT group, blood glucose levels at both 60 (5.4+/-1.7 mmol/l) and 120 (5.0+/-1.1 mmol/l) min increased significantly relative to baseline (4.1+/-0.4 mmol/l; both P<0.001) and, similarly, insulin levels were higher at both 60 (30.1+/-21.3 m-units/l) and 120 (34.9+/-23.6 m-units/l) min compared with baseline (4.7+/-4.3 m-units/l; both P<0.001). Although blood glucose and insulin levels changed, FMD did not significantly differ between time-points or between groups. In summary, despite significantly elevated glucose and insulin concentrations in these subjects, we observed no change in vascular function, suggesting that acute elevations of glucose and insulin within the clinically normal range are not associated with impaired vascular function in vivo.

Administration, Oral↗