Clinical and Metabolic Characteristics of South Asians and Men and Women of European Ancestry

Persons from the Indian subcontinent have elevated coronary heart disease risk. We measured insulin resistance with the insulin suppression test in 22 Asian Indian men and women and an equal number of control subjects of European ancestry matched for age and body mass index. Asian men and women had increased glucose and insulin responses to oral glucose tolerance tests (P<.05 by ANOVA) and had approximately 60% higher steady-state plasma glucose levels during the insulin suppression test (P<.001 by ANOVA), consistent with insulin resistance. In response to mixed meals, Asian women had higher plasma free fatty acids and glycerol concentrations than women of European ancestry (P<.02 by ANOVA), whereas Asian Indian men had similar free fatty acid and glycerol levels compared with men of European ancestry despite higher plasma insulin levels. Thus, Persons from the Indian subcontinent are at increased risk for coronary heart disease (CHD) death' even though they lack an excess of some traditional risk factors for CHD, specifically smoking, high-fat diet, and elevated low-density lipoprotein (LDL) cholesterol. McKeigue et al and others report that compared with British men and women, Asian Indian men and women have lower fasting plasma high-density lipoprotein (HDL) cholesterol, higher triglycerides, and higher glucose and insulin concentrations, both fasting and in response to an oral glucose load. This cluster of risk factors is postulated to have its basis in insulin resistance. The current study is the first to directly measure insulin resistance in Asian Indians. Plasma lipid and lipoproteins that are associated with insulin resistance were also measured. Methods Subjects Thirteen men and nine women born on the Indian subcontinent were matched for age and body mass index (BMI) with equal numbers of men and women of European ancestry. All subjects were recruited through newspaper advertisements for a study of relations of blood sugar and insulin to CHD risk factors. Subjects were excluded if they had diabetes by history or a fasting plasma glucose concentration >6.4 mmol/L. Other Received July 9, 1993; revision accepted March 10, 1994. From the Department of Medicine, Stanford University School of Medicine (A.L., J.L.J., P.C.M., P.S., Y.-D.I.C, G.M.R.), and the Geriatric Research, Education and Clinical Center, Department of Veterans Affairs Medical Center (G.M.R.), Palo Alto, Calif. Correspondence and reprint requests to Ami Laws, MD, GRECC 182B, Palo Alto Department o: Veterans Affairs Medical Center, 3801 Miranda Ave, Palo Alto, CA 94304. results in both sexes were consistent with resistance to insulin suppression of free fatty acid levels in Asian Indians. Asian Indians of both sexes had higher fasting plasma triglyceride (P<.01) and lower high-density lipoprotein cholesterol (P<.01) concentrations than men and women of European ancestry. Resistance to insulin-stimulated glucose uptake and to insulin suppression of free fatty acid levels in Asian Indians is associated with a number of metabolic abnormalities that are demonstrated risk factors for coronary heart disease, including increased glucose, insulin, and triglyceride concentrations and decreased high-density lipoprotein cholesterol concentrations. (Arterioscler Thromb. 1994;14:917-922.)