Inventi Impact: Endocrinology

Inventi:hdb/17281/15

Ethnic Differences in Insulin Sensitivity and Beta-cell Function among Asian Men

BACKGROUND AND OBJECTIVES: Lean Asian Indians are less insulin sensitive compared with Chinese and Malays, but the\npancreatic beta-cell function among these ethnic groups has yet to be studied in depth. We aimed to study beta-cell function in\nrelation to insulin sensitivity among individuals of Chinese, Malay and Asian-Indian ethnicity living in Singapore.\nSUBJECTS AND METHODS: This is a sub-group analysis of 59 normoglycemic lean (body mass index (BMI) o23 kgm?2) adult\nmales (14 Chinese, 21 Malays and 24 Asian Indians) from the Singapore Adults Metabolism Study. Insulin sensitivity was determined\nusing fasting state indices (homeostatic model assessment�insulin resistance), the euglycemic-hyperinsulinemic clamp (ISI-clamp)\nand a liquid mixed-meal tolerance test (LMMTT) (Matsuda insulin sensitivity index (ISI-Mat)). Beta-cell function was assessed using\nfasting state indices (homeostatic model assessment�beta-cell function) and from the LMMTT (insulinogenic index and insulin\nsecretion index). The oral disposition index (DI), a measure of beta-cell function relative to insulin sensitivity during the LMMTT, was\ncalculated as a product of ISI-Mat and insulin secretion index.\nRESULTS: Asian Indians had higher waist circumference and percent body fat than Chinese and Malays despite similar BMI. Overall,\nAsian Indians were the least insulin sensitive whereas the Chinese were most insulin sensitive. Asian Indians had higher beta-cell\nfunction compared with Chinese or Malays but these were not statistically different. Malays had the highest incremental area under\nthe curve for glucose during LMMTT compared with Asian Indians and Chinese. However, there were no significant ethnic differences\nin the incremental insulin area under the curve. The oral DI was the lowest in Malays, followed by Asian Indians and Chinese.\nCONCLUSION: Among lean Asians, Chinese are the most insulin sensitive whereas Asian Indians are the least insulin sensitive.\nHowever, Malays demonstrate higher postprandial glucose excursion with lower beta-cell response compare with Chinese or Asian\nIndians. The paths leading to type 2 diabetes mellitus might differ between these Asian ethnic groups.