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.

Randomised controlled trial evaluating lifestyle interventions in people with impaired glucose tolerance

Aim

To evaluate the effectiveness of lifestyle interventions in people with impaired glucose tolerance (IGT).
Methods

Participants with IGT (n = 78), diagnosed on two consecutive oral glucose tolerance tests (OGTTs), were randomly assigned to a 2-year lifestyle intervention or to a control group. Main outcome measures were changes from baseline in: nutrient intake; physical activity; anthropometry, glucose tolerance and insulin sensitivity. Measurements were repeated at 6, 12 and 24 months follow-up.
Results

After 24 months follow-up, there was a significant fall in total fat consumption (difference in change between groups (Δ intervention − Δ control) = −17.9, 95% confidence interval (CI) −33.6 to −2.1 g/day) as a result of the intervention. Body mass was significantly lower in the intervention group compared with controls after 6 months (−1.6, 95% CI −2.9 to −0.4 kg) and 24 months (−3.3, 95% CI −5.7 to −0.89 kg). Whole body insulin sensitivity, assessed by the short insulin tolerance test (ITT), improved after 12 months in the intervention group (0.52, 95% CI 0.15–0.89%/min).
Conclusions

These findings complement the findings of the Finnish Diabetes Prevention Study and the American Diabetes Prevention Study, both of which tested intensive interventions, by showing that pragmatic lifestyle interventions result in improvements in obesity and whole body insulin sensitivity in individuals with IGT, without change in other cardiovascular risk factors.

The rising prevalence of diabetes and impaired glucose tolerance : the Australian diabetes, obesity and lifestyle study

OBJECTIVE—To determine the population-based prevalence of diabetes and other categories of glucose intolerance (impaired glucose tolerance [IGT] and impaired fasting glucose [IFG]) in Australia and to compare the prevalence with previous Australian data.

RESEARCH DESIGN AND METHODS—A national sample involving 11,247 participants aged >=25 years living in 42 randomly selected areas from the six states and the Northern Territory were examined in a cross-sectional survey using the 75-g oral glucose tolerance test to assess fasting and 2-h plasma glucose concentrations. The World Health Organization diagnostic criteria were used to determine the prevalence of abnormal glucose tolerance.

RESULTS—The prevalence of diabetes in Australia was 8.0% in men and 6.8% in women, and an additional 17.4% of men and 15.4% of women had IGT or IFG. Even in the youngest age group (25–34 years), 5.7% of subjects had abnormal glucose tolerance. The overall diabetes prevalence in Australia was 7.4%, and an additional 16.4% had IGT or IFG. Diabetes prevalence has more than doubled since 1981, and this is only partially explained by changes in age profile and obesity.

CONCLUSIONS—Australia has a rapidly rising prevalence of diabetes and other categories of abnormal glucose tolerance. The prevalence of abnormal glucose tolerance in Australia is one of the highest yet reported from a developed nation with a predominantly Europid background.

Abbreviations: 2hPG, 2-h plasma glucose • AusDiab, Australian Diabetes, Obesity and Lifestyle Study • CD, Census Collector District • FPG, fasting plasma glucose • IFG, impaired fasting glucose • IGT, impaired glucose tolerance • KDM, known diabetes mellitus • NDM, newly diagnosed diabetes mellitus • OGTT, oral glucose tolerance test • WHO, World Health Organization

Risk of cardiovascular and all-cause mortality in individuals with diabetes mellitus, impaired fasting glucose, and impaired glucose tolerance. The Australian Diabetes, Obesity and Lifestyle Study (AusDiab)

Background--Diabetes mellitus increases the risk of cardiovascular disease (CVD) and all-cause mortality. The relationship between milder elevations of blood glucose and mortality is less clear. This study investigated whether impaired fasting glucose and impaired glucose tolerance, as well as diabetes mellitus, increase the risk of all-cause and CVD mortality.

Methods and Results--In 1999 to 2000, glucose tolerance status was determined in 10 428 participants of the Australian Diabetes, Obesity, and Lifestyle Study (AusDiab). After a median follow-up of 5.2 years, 298 deaths occurred (88 CVD deaths). Compared with those with normal glucose tolerance, the adjusted all-cause mortality hazard ratios (HRs) and 95% confidence intervals (CIs) for known diabetes mellitus and newly diagnosed diabetes mellitus were 2.3 (1.6 to 3.2) and 1.3 (0.9 to 2.0), respectively. The risk of death was also increased in those with impaired fasting glucose (HR 1.6, 95% CI 1.0 to 2.4) and impaired glucose tolerance (HR 1.5, 95% CI 1.1 to 2.0). Sixty-five percent of all those who died of CVD had known diabetes mellitus, newly diagnosed diabetes mellitus, impaired fasting glucose, or impaired glucose tolerance at baseline. Known diabetes mellitus (HR 2.6, 95% CI 1.4 to 4.7) and impaired fasting glucose (HR 2.5, 95% CI 1.2 to 5.1) were independent predictors for CVD mortality after adjustment for age, sex, and other traditional CVD risk factors, but impaired glucose tolerance was not (HR 1.2, 95% CI 0.7 to 2.2).

Conclusions--This study emphasizes the strong association between abnormal glucose metabolism and mortality, and it suggests that this condition contributes to a large number of CVD deaths in the general population. CVD prevention may be warranted in people with all categories of abnormal glucose metabolism.

Gender differences in the prevalence of impaired fasting glycaemia and impaired glucose tolerance in Mauritius. Does sex matter?

Objective: To examine gender differences in the characteristics and prevalence of various categories of glucose tolerance in a population study in Mauritius.

Research design and methods: In 1998, a community-based cross-sectional survey was conducted in Mauritius. Categories of glucose metabolism were determined in 5388 adults, with an oral glucose tolerance test given to those who did not have previously diagnosed diabetes (n = 4036). Other cardiovascular risk factors were assessed among those without known diabetes.

Results: For men and women the prevalence of diabetes (22.0 vs. 21.8%, respectively) and the prevalence of coexisting impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) (3.2 vs. 2.9%) were similar. However, men were twice as likely as women to have isolated IFG [5.1% (4.2–6.0) vs. 2.9% (2.3–3.5)], despite being younger, thinner and with lower plasma insulin but higher lipids. Conversely, the prevalence of isolated IGT was lower in men [9.0% (7.9–10.2) vs. 13.9% (12.6–15.1)]. Among non-diabetic individuals, fasting glucose was higher in men than women, whereas 2-h glucose was higher in women. In people without diabetes, women had significantly higher body mass index, beta cell function (HOMA-B), fasting and 2-h insulin than men and significantly lower waist-hip ratios, waist circumference, insulin sensitivity (HOMA-S) and triglycerides.

Conclusion: In Mauritius, the distribution of impaired glucose metabolism differs by sex. The observation that IFG is more prevalent in men and IGT more prevalent in women raises important questions about their underlying aetiology and the ability of the current glucose thresholds to equally identify men and women at high-risk of developing diabetes. IFG should be seen as a complimentary category of abnormal glucose tolerance, rather than a replacement for IGT.

The effectiveness of a brief intervention using a pedometer and step-recording diary in promoting physical activity in people diagnosed with type 2 diabetes or impaired glucose tolerance

Issue addressed: To evaluate the effectiveness of a brief intervention using a pedometer and step-recording diary on promoting physical activity in people with type 2 diabetes or impaired glucose tolerance (IGT). Methods: People with type 2 diabetes or IGT who attended the Illawarra Diabetes Service were invited to participate. Participants in the intervention group received a pedometer and a diary to record their daily steps for a two-week period. Both the intervention and comparison group received advice on physical activity. Physical activity levels were measured using the Active Australia Survey at baseline, and at two and 20 weeks. Results: A total of 226 participants were recruited. At two-week follow-up the mean self-reported minutes of walking was significantly higher in the intervention group than the comparison group (223 minutes versus 164 minutes; p=0.01), as was the percentage of intervention participants achieving recommended levels of moderate-intensity physical activity (63.5% versus 41.8%, p=0.02) and the percentage of intervention participants achieving adequate levels of total physical activity (68.9% versus 48.0%, p=0.04). There were no differences between study groups for any physical activity measure at 20-week follow-up. Conclusions: A pedometer and a step-recording diary were useful tools to promote short-term increase in physical activity in people diagnosed with type 2 diabetes or IGT. Future studies need to examine whether a longer intervention, individualised physical activity counselling and support for achieving step goals could result in increasing physical activity over the long term.