Insulin secretion and insulin action in Taiwanese with type 2 diabetes

In contrast to the United State, type 2 diabetes appears to be a common occurrence in non-obese Asians. In order to evaluate the possibility that this epidemiologic difference was indicative of a basic metabolic phenomenon, estimates of insulin secretion and insulin action were generated in 32 Chinese males, 16 with type 2 diabetes and 16 with normal glucose tolerance. Half of the individuals in each diagnostic category were obese (body mass index greater than 28 kg/m2) and half were non-obese (less than 26 kg/m2). Plasma glucose responses to a 75-g oral glucose challenge were significantly higher in patients with type 2 diabetes, but did not vary significantly within either group as a function of obesity. Plasma insulin concentrations were lower than normal when patients with type 2 diabetes were compared to their weight-matched controls. In addition, the absolute insulin values also varied as a function of body weight, with higher plasma insulin concentrations observed in the obese individuals. Insulin action was estimated by determination of the steady-state plasma insulin (SSPI) and glucose (SSPG) concentrations during the last 60 min of a continuous 180-min intravenous infusion of somatostatin, crystalline insulin, and glucose. Under these conditions endogenous insulin secretion is suppressed, SSPI concentrations are similar in all individuals, and SSPG concentrations provide a quantitative estimate of insulin-stimulated glucose disposal. The results of these studies indicated that patients with type 2 diabetes had significantly elevated SSPG concentrations as compared to normals, and this was true whether the diabetic subjects were obese or non-obese.(ABSTRACT TRUNCATED AT 250 WORDS)