Abdominal Adiposity and Diabetes Risk

The Importance of Precise Measures and Longitudinal Studies

Obesity is perhaps the longest studied and best described risk factor for type 2 diabetes. Epidemiologic investigations have consistently shown an independent increased risk for diabetes associated with overweight and obesity, with clear dose response patterning across categories of increasing body mass. While the importance of increased body mass in diabetes etiology is unequivocal, it has been recognized for some time that the distribution of body fat provides additional resolution regarding diabetes risk. In 1947, Vague (1) noted that an android (male or upper body) pattern of obesity was associated with a poorer metabolic profile compared with a gynecoid (lower body) pattern. These clinical observations regarding the detrimental health effects of central or upper body obesity were subsequently reinforced by the results of large prospective epidemiological studies of diabetes incidence, in which fat patterning of subjects was estimated using body surface measurements, specifically waist and hip circumferences and skinfold thicknesses (2–5). While these and other studies have reported superior prediction of diabetes with waist circumference or waist-to-hip ratio compared with BMI, it is notable that this is far from a universal finding. Indeed, a recent meta-analysis of 32 studies concluded that BMI, waist circumference, and waist-to-hip ratio had similar associations with incident diabetes (6).

This lack of clarity in the epidemiologic literature regarding optimal measures of obesity for studies of diabetes risk is due at least in part to the nature of these proxy (surrogate) measurements. Body surface measures such as waist circumference do not distinguish between the various adipose tissue depots, which are known to have differences in biologic function. Specifically, there can be sizable differences in the amounts of visceral (VAT) and subcutaneous adipose tissue (SAT) …