Decreased fatty acid availability following exercise training may contribute to improved insulin sensitivity of glucose metabolism
Posted: January 10, 2007

The hierarchy of mechanisms underlying the improvement in insulin sensitivity following exercise training is not established. Such an improvement may ensue from reduction in circulating peripheral (from subcutaneous fat) and/or portal (from visceral fat) non-esterified fatty acids (NEFAs) generated from insulin-sensitive lipolysis, from lesser obesity and adipokines production, or from reduced lipid accumulation in liver and muscle. To investigate the effects of exercise on hepatic or peripheral insulin sensitivity and on potential adaptive changes in fatty acid metabolism, visceral fat or liver and muscle triacylglycerol content, 17 sedentary overweight males were randomised to either a 6-week exercise programme or to a control group. The insulin sensitivity of palmitic acid production rate (Ra), glycerol Ra, endogenous glucose Ra (EGP), glucose uptake and glucose metabolic clearance rate were measured before and after the 6 weeks with a two-step hyperinsulinaemic-euglycaemic clamp. After 6 weeks, fasting glycerol, palmitic acid Ra and NEFAs were significantly decreased in the exercise group but not in the control group (P=0.003, P=0.042 and P=0.005, respectively). The effects of low-dose insulin on EGP and of high-dose insulin on glucose uptake and metabolic clearance rate were increased in the exercise group but not in the control group (P=0.026, P=0.007 and P=0.04, respectively). Muscle triacylglycerol and liver fat remained unchanged in both groups. Decreased availability of circulating NEFAs may thus contribute to the observed improvement in the insulin sensitivity of EGP and glucose uptake following exercise training.

Overweight and obesity correlated with poor socio-economic status in 4-5-year-old children across Australia
Posted: January 5, 2007

A nationally representative sample of 4983 4-5-year-old Australian children was used to estimate the prevalence of obesity and overweight, and to investigate associations between socio-economic status and overweight/obesity (International Obesity TaskForce definitions) and waist circumference. As a result, 15.2% of Australian preschoolers were estimated to be overweight and 5.5% obese. Multivariable logistic regression analysis revealed that (i) speaking a language other than English, (ii) indigenous status and (iii) lower disadvantage quintile were the best independent predictors of higher body mass index status, with children in the lowest quintile of social disadvantage having 47% higher odds of being in a heavier body mass index category when compared with those in the highest quintile. Waist circumference was not linked to any socioeconomic variable.

Higher-than-optimal blood glucose levels as a leading cause for cardiovascular mortality worldwide
Posted: January 1, 2007

Population-level effects of all higher-than-optimum blood glucose on mortality from ischaemic heart disease and stroke were studied by collating blood glucose data from health surveys in 52 countries. Relative risks for ischaemic heart disease and stroke mortality were drawn from a meta-analysis including more than 200000 participants from Asia-Pacific. Besides 959000 deaths directly linked to diabetes, 21% of all deaths from ischaemic heart disease and 13% of all deaths from stroke were attributable to high blood glucose. Higher-than-optimum blood glucose was a leading cause of cardiovascular mortality in most regions. The largest number of deaths from ischaemic heart disease attributable to high blood glucose was in low-and-middle-income countries of South Asia, Europe and Central Asia whereas the largest number of deaths from stroke attributable to high blood glucose was in South Asia, East Asia and Pacific.

Elevated serum levels of adiponectin associated with a lower risk of coronary heart disease
Posted: December 31, 2006

Numerous studies indicate an inverse relationship between adiponectin and obesity or coronary heart disease (CHD) prevalence. In a population-based cohort study conducted in Sweden, 832 healthy men aged 70 years were followed up for 10.4 years, using national registry data. Baseline measurements included anthropometry, blood pressure, smoking, serum lipids, euglycaemic insulin clamp and fasting serum adiponectin. Outcome measures were defined as death or first time hospitalization for coronary heart disease. In a multivariable analysis, serum adiponectin was shown to be associated with a lower risk for CHD (hazard ratio =0.81; CI=0.66-0.99), independently of other well-known risk factors.

Increasing trends in waist circumference and waist-height ratio among US children and adolescents
Posted: December 30, 2006

Abdominal obesity is increasingly thought as better predictor than overall obesity for the risk of cardiovascular disease and type 2 diabetes. Simple surrogate estimates of abdominal obesity include waist circumference and waist-height ratio. Representative samples from the National Health and Nutrition Examination Survey were examined between 1988-1994 and 1999-2004 to estimate the mean waist circumference and waist-height ratio of boys and girls in 4 different age groups (2-5 years, 6-11 years, 12-17 years and 18-19 years). During the observation period, the unadjusted mean waist circumference for the different age groups greatly increased from 50.7, 61.9, 76.8, and 81.3 cm to 51.9, 64.5, 79.8 and 86.6 cm for boys and from 51.0, 61.7, 75.0, and 77.7 cm to 51.8, 64.7, 78.9, and 83.9 cm for girls, respectively, with similar changes in waist-height ratio for boys and girls at each age group.

Breastfeeding in infancy associated with a reduced risk of type 2 diabetes
Posted: December 29, 2006

Observational data suggest that breastfeeding in infancy &/or decreased exposure to cow's milk may reduce the prevalence of type 1 and type 2 diabetes in later life. To assess the influence of breastfeeding on type 2 diabetes and blood glucose and insulin concentrations, a systematic review of published studies was carried out, including 23 papers focused on the relation between infant feeding and type 2 diabetes in later life. Estimates were pooled using fixed-effects models, differences <0 and ratios <1 implying a beneficial effect of breastfeeding. Compared with formula fed subjects, breastfed subjects had a lower risk of type 2 diabetes in later life (P=0.003); breastfed children and adults had marginally lower fasting insulin concentrations (P=0.13) whereas there was no difference in fasting glucose concentrations; breastfed infants had lower preprandial glucose and insulin concentrations.