Acute exercise and impaired glucose tolerance in obese humans

BACKGROUND: Individuals with impaired glucose tolerance (IGT) have a greater risk of developing diabetes and cardiovascular disease compared with those with normal glycemic control. The aim of this study was to examine the effects of acute aerobic exercise on glycemia, regional arterial stiffness, and oxidative stress in obese subjects with IGT.

Effect of pioglitazone on endothelial function in impaired glucose tolerance

Aim: Flow-mediated dilation (FMD) is a surrogate marker of endothelial function, which has been proposed as a barometer of vascular health. Impaired microvascular response to reactive hyperaemia is thought to be the mechanism behind reduced shear stress and subsequently impaired FMD, which has been associated with cardiovascular events. This study aims to assess the effect of pioglitazone on the vasculature of patients with impaired glucose tolerance (IGT).

Materials and Methods: Forty IGT patients with no cardiovascular disease were compared with 24 healthy age- and sex-matched controls. Endothelial function was assessed using FMD of the brachial artery. Adiponectin (ADN) levels were measured and insulin sensitivity was calculated using homeostasis model assessment of insulin resistance (HOMA-IR). A randomised double-blind placebo-controlled trial of the IGT subjects was then performed, with subjects receiving either pioglitazone 30 mg od or matched placebo for 12 weeks before the measurements were repeated.

Results: The IGT subjects had a significantly impaired FMD compared with the controls (p < 0.001). Diastolic shear stress (DSS) was also significantly reduced in IGT (p = 0.04). High molecular weight (HMW) ADN was significantly lower in the IGT group than in controls (p = 0.03). On analysis of the IGT group after 12 weeks treatment, FMD was significantly increased in the pioglitazone group compared with placebo (p = 0.03) as was endothelium-independent dilation (EID) (p = 0.03). A significant increase in total ADN (p < 0.001), HMW ADN (p < 0.001) and HMW/total ratio (p = 0.001) occurred in the pioglitazone group compared with placebo.

Conclusions: Pioglitazone improved endothelial function in IGT. Treatment with pioglitazone may reduce the risk of cardiovascular disease in this patient group.

Ocular blood flow analysis detects microvascular abnormalities in impaired glucose tolerance.

Objective: Waveform analysis has been used to assess vascular resistance and predict cardiovascular events. We aimed to identify microvascular abnormalities in patients with impaired glucose tolerance (IGT) using ocular waveform analysis. The effects of pioglitazone were also assessed. Methods: Forty patients with IGT and twenty-four controls were studied. Doppler velocity recordings were obtained from the central retinal, ophthalmic and common carotid arteries, and sampled at 200 Hz. A discrete wavelet-based analysis method was employed to quantify waveforms. The resistive index (RI),was also determined. Patients with IGT were randomised to pioglitazone or placebo and measurements repeated after 12 weeks treatment. Results: In the ocular waveforms, significant differences in power spectra were observed in frequency band four (corresponding to frequencies between 6.25 and 12.50 Hz) between groups (p

A low glycaemic load breakfast can attenuate cognitive impairments observed in middle aged obese females with impaired glucose tolerance.

Increased central adiposity and abnormalities in glucose tolerance preceding type 2 diabetes can have demonstrable negative effects on cognitive function, even in ostensibly healthy, middle-aged females. The potential for GL manipulations to modulate glycaemic response and cognitive function in type 2 diabetes and obesity merits further investigation..

Type 2 diabetes and impaired glucose tolerance are associated with word memory source monitoring recollection deficits but not simple recognition familiarity deficits following water, low glycaemic load, and high glycaemic load breakfasts.

Isolated source monitoring recollection deficits indicate that abnormalities in glucose metabolism are not detrimental for global episodic memory processes. This enhances our understanding of how metabolic disorders are associated with memory impairments.

Brazilian individuals with impaired glucose tolerance are characterized by impaired insulin secretion

Background: To better understand the pathogenesis of type 2 diabetes mellitus, insulin secretion and insulin sensitivity (IS) were evaluated in white Brazilians with impaired glucose tolerance (IGT), using the oral glucose tolerance test (OGTT) and the hyperglycemic clamp technique.Methods: Twenty-five IGT subjects were individually matched with normal glucose-tolerant (NGT) subjects for demographic characteristics, At first, they were submitted to the OGTT and plasma glucose and insulin were measured. of the 25 pairs, 20 could participate in the hyperglycemic clamp procedures, at a second visit. All participants had their plasma glucose levels equally increased to 180 mg/dl; this was maintained for three hours by variable glucose infusion. During the procedure, plasma glucose and insulin were measured at established intervals.Results: In the postabsorptive state, the IGT subjects presented higher levels of plasma glucose, blood HbA(1) and serum triglycerides, but similar plasma insulin levels. After the oral glucose load, early and total insulin release, in relation to glucose levels, were respectively, 43 and 67% lower in the IGT individuals, the index of whole-body IS was increased in the IGT individuals (4.36 +/- 1.71 vs 3.61 +/- 1.28 mg(-1).muU(-1) 100.ml(2); p < 0.05). By the hyperglycemic clamp technique first- (82 &PLUSMN; 26 vs 215 &PLUSMN; 88 μU/ml; p < 0.001) and second- (36 +/- 19 vs 73 +/- 44 muU/ml; p < 0.05) phases of insulin secretion was decreased in the IGT individuals, especially the first one. However, the groups did not differ in relation to the IS: IGT = 13.52 &PLUSMN; 7.27 and NGT = 9.96 &PLUSMN; 6.70 mg.ml/kg.μU.min(-1); p > 0.05. Functional relationship of IS (y) on first-phase insulin release (x) showed a smaller (p < 0,05) regression coefficient for the IGT group.Conclusion: Brazilians with IGT well-matched with NGT ones were characterized by impaired first- and second-phase insulin secretion (mainly the former), while defects in IS were not evident.

Long-term nutrition education reduces several risk factors for type 2 diabetes mellitus in Brazilians with impaired glucose tolerance

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Daytime variations in glucose tolerance in people with impaired glucose tolerance

To determine whether glucose tolerance varies throughout the day in people with impaired glucose tolerance (IGT). We studied 15 healthy IGT, and 18 matched normal glucose tolerant (NGT) individuals. Blood samples were taken every 30-120 min during a 24 h period in which all individuals had three mixed meals and nocturnal sleep. We measured glucose, free fatty acids, specific insulin, intact proinsulin, cortisol and growth hormone. Variable responses were considered as concentrations and areas under the curves. Comparison between the groups was by Student's t-test, Mann-Whitney, and analysis of variance. Higher total glucose response, inappropriate normal total insulin response, and unproportionally increased proinsulin total response were observed in the IGT group. Lower glucose tolerance occurred in IGT after dinner, as in the NGT, and after breakfast associated with increased insulin response after breakfast, and similar proinsulin response after all three meals. IGT had higher glucose response than NGT after breakfast and lunch, similar insulin responses, and increased proinsulin-insulin ratio after all three meals. Data from this study demonstrate that IGT individuals present lower glucose tolerance in the evening, as those with NGT, and in the morning, as reported in patients with type 2 diabetes. © 2006 Elsevier B.V. All rights reserved.