Insulin resistance and vascular dysfunction in nondiabetic Asian Indians.
Asian Indians are at higher risk for diabetes and cardiovascular disease than European Caucasians. To examine the pathophysiology of this increased risk, we measured insulin sensitivity, cardiovascular risk factors, fat distribution, and endothelium-dependent (reactive hyperemia) and -independent (nitroglycerin) vasodilation before and after a 2-h hyperinsulinemic clamp (40 mU/m(2).min) in 25 nondiabetic Asian Indians and 15 Caucasians with similar age and body mass index. Asian Indians had higher fasting insulin than Caucasians (6.7 +/- 0.8 vs. 3.7 +/- 0.3 microU/ml, P = 0.007) but similar FPG (90 +/- 2 vs. 88 +/- 2 mg/dl). Glucose uptake during the clamp was markedly reduced in Asian Indians vs. Caucasians (4.5 +/- 0.3 vs. 7.5 +/- 0.4 mg/kg x min, P < 0.0001). During the clamp, basal brachial artery diameter increased less in Asian Indians vs. Caucasians (2.6 +/- 1.0 vs. 5.7 +/- 1.0%, P = 0.04), and the reduction was correlated with the impairment in insulin sensitivity (r = 0.38, P = 0.04). In contrast, vasodilatory responses to reactive hyperemia and nitroglycerin were similar in Asian Indians and Caucasians both before and during hyperinsulinemia. Plasminogen activator inhibitor-1 and FFA were significantly elevated and adiponectin was significantly lower in Asian Indians vs. Caucasians, and there were trends toward higher low-density lipoprotein and triglycerides, lower high-density lipoprotein, and increased total, sc, and visceral fat. These risk factors were all significantly correlated with insulin sensitivity. Thus, apparently healthy Asian Indians have severe insulin resistance, dyslipidemia, elevated plasminogen activator inhibitor-1, impaired insulin-mediated vasodilation, and trends toward altered body fat distribution. These abnormalities may contribute to the increased risk of diabetes and cardiovascular disease in this population.
Raji
Annaswamy
A
Division of Endocrinology, Diabetes, and Metabolism, Brigham and Women's Hospital, 221 Longwood Avenue, Boston, Massachusetts 02115, USA. araji@partners.org
Gerhard-Herman
Marie D
MD
Warren
Mercedes
M
Silverman
Stuart G
SG
Raptopoulos
Vassilios
V
Mantzoros
Christos S
CS
Simonson
Donald C
DC
D000005:Abdomen; D052242:Adiponectin; D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000328:Adult; D044466:Asian People; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D002318:Cardiovascular Diseases / Q000209:etiology; D016022:Case-Control Studies; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D007194:India / Q000208:ethnology; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D036341:Intercellular Signaling Peptides and Proteins; D008875:Middle Aged; D011506:Proteins / Q000378:metabolism; D011859:Radiography; D012307:Risk Factors; D040521:Subcutaneous Tissue; D014280:Triglycerides / Q000097:blood; D014463:Ultrasonography; D014481:United States; D014664:Vasodilation; D044465:White People
D052242:Adiponectin; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D014280:Triglycerides