Lean, nondiabetic Asian Indians have decreased insulin sensitivity and insulin clearance, and raised leptin compared to Caucasians and Chinese subjects

Abstract

OBJECTIVE:To study and compare the insulin sensitivity of healthy, nondiabetic Asian Indians with that of two other ethnic groups (Caucasian and Chinese) living in Singapore. DESIGN: Study of insulin sensitivity using euglycaemic hyperinsulinaemic glucose clamp. SUBJECTS: A total of 10 healthy, lean, young male subjects of each ethnic group, matched for age, body mass index (BMI) and physical activity. They all had normal glucose tolerance and had no family history of diabetes. MEASUREMENTS: Anthropometric parameters (BMI, waist-hip ratio (WHR) and percentage body fat (PBF)), fasting lipid profile and leptin concentration, insulin sensitivity index, and insulin clearance. , diastolic blood pressure (P ¼ 0.036), fasting insulin (Po0.006) and fasting triglyceride (P ¼ 0.022). Stepwise regression analysis showed that ethnicity was the only significant independent determinant variable for the differences in insulin sensitivity index (P ¼ 0.008). CONCLUSION: Healthy lean nondiabetic Indians were more insulin resistant compared to other ethnic groups despite the similarity in living environment. These findings may warrant preventive health-care strategies for type II diabetes and coronary artery disease to target Indians at an earlier stage compared to other ethnic groups.

Can body fat distribution, adiponectin levels and inflammation explain differences in insulin resistance between ethnic Chinese, Malays and Asian Indians?

“…Finally, other adipokines and inflammatory markers such as retinol binding protein-4, interleukin-6, leptin and resistin may contribute to ethnic differences in insulin resistance and were not measured in our study. 47 In summary, our results suggest that the higher degree of insulin resistance in Malays compared with Chinese was due to general adiposity. When Asian Indians were compared with Chinese, greater general adiposity, abdominal fat distribution, and higher CRP independent of adiposity appeared to contribute to the greater insulin resistance in Asian Indians.…”

“…46 More specifically, although culturally distinct, Malays in Singapore had a greater genetic similarity with Chinese than Asian Indians. 46,47 Greater general adiposity of Malays as compared with Chinese explained their greater insulin resistance in our study and targeting excess weight gain in Malays should have high priority in public health efforts for chronic disease prevention. 45 Compared with ordinary regression analysis, path analysis has the advantage that it allows examination of the potential causal processes underlying an observed relationship and to estimate the relative importance of alternative paths of influence in a complicated system.…”

Born with low birth weight in rural Southern India: what are the metabolic consequences 20 years later?

“…Furthermore, the Indian patient with type 2 diabetes (T2D) tends to be diagnosed a decade earlier, is characterised by a lower body mass index (BMI) and is more centrally obese when compared with patients of Caucasian origin (3). Additionally, non-diabetic south Asians are more insulin resistant (4,5) and have an adverse fat distribution with more abdominal, hepatic and intramyocellular fat (6, 7) when compared with those from other ethnic groups with a similar BMI.…”

MECHANISMS IN ENDOCRINOLOGY: Pathogenesis of type 2 diabetes in South Asians

“…Multiple studies have repeatedly shown that South Asians have higher fasting insulin concentrations compared with other ethnic groups regardless of age, gender, or BMI, suggesting a higher rate of IR in this population (15,16,17,18,19,20,21,22,23,24,25). Already in South Asian neonates' the fasting insulin levels are markedly higher compared with European White Caucasian neonates' (26,27), and fasting insulin remains higher in school children (28,29) and teenagers (30).…”