Increases in Waist Circumference and Weight Predicts Incident Diabetes

Alain Gautier, MD, from Center Hospitalier Universitaire de Rennes in France, and colleagues write, "Individuals with impaired fasting glucose (IFG) are at high risk for Type 2 diabetes," from the Data from an Epidemiological Study on the Insulin Resistance syndrome (D.E.S.I.R.) Study Group. "Although visceral adiposity and waist circumference are strong risk factors for Type 2 diabetes, the consequence of an increase in waist circumference among individuals with IFG at baseline has not been fully investigated, in particular in those who are not overweight or obese at baseline. This report investigates the relative importance of increases in waist circumference and weight on progression to diabetes, in individuals with baseline IFG, according to baseline BMI [body mass index] strata."

Using the D.E.S.I.R. cohort, the investigators studied the 9-year incidence of diabetes in 979 men and women with baseline IFG. After adjustment for risk factors at baseline, increases in both waist circumference and weight were significantly associated with diabetes incidence. Standardized odds ratios (ORs) were 1.79 for waist circumference (95% confidence interval [CI], 1.45 - 2.21) and 1.86 for weight (95% CI, 1.51 - 2.30).

For patients with a BMI of less than 25 kg/m² at baseline, the effect of increase in waist circumference was greater (OR, 2.40; 95% CI, 1.63 - 3.52) vs patients with a BMI of 25 kg/m² or more at baseline (OR, 1.66; 95% CI, 1.28 - 2.16). Adjustment for concurrent changes in either insulinemia or the updated version of the homeostasis model assessment of insulin resistance (HOMA2-IR) index did not abolish the difference in effect based on initial BMI. The effect of weight change was similar in both BMI groups.

"In IFG individuals, it is important to monitor and prevent increases in waist circumference, in particular for those with BMI<25 kg/m²," the study authors said.

The study authors write, "Impaired β-cell function is considered an important characteristic in individuals with IFG and reduced insulin secretion has been shown to be a prominent mechanism leading to diabetes in lean individuals.... We speculate that an increase in waist circumference may induce further alterations in insulin secretion beyond that inherent in a worsening insulin resistance. Potential mechanisms may involve β-cell lipotoxicity through enhanced free fatty acid release from adipose tissue."

Diabetes Care. Published online May 18, 2010. Abstract