Ethnic Variation in Obesity Risk

Yesterday, I attended the annual Spring Meeting of CANNeCTIN (Canadian Network and Centre for Trials Internationally), a national network funded by the CIHR/CFI Clinical Research Initiative program to improve the prevention and treatment of cardiac and vascular diseases and diabetes.

CANNeCTIN is jointly led by Dr. Salim Yusuf, from Hamilton Health Sciences and McMaster University, and Dr. John Cairns, from the University of British Columbia. CANNeCTIN facilitates the development, conduct and leadership of large international clinical trials, registries and epidemiologic studies across Canada and the world.

As it so happens, yesterday, also saw the online publication in Diabetes Care of a paper I was involved in during my time in Hamilton on the ethnic variation of risk factors associated with obesity.

In this paper, we looked at the relationship between body weight (BMI), adipokines, and insulin resistance in 1,176 South Asian, Chinese, Aboriginal, and European Canadians in the SHARE study (Study of Health Assessment and Risk in Ethnic groups).

Adjusted mean adiponectin (a protein secreted by fat cells that improves insulin sensitivity) concentration was significantly higher in Europeans [12.9] and Aboriginals [11.8] compared to South Asians [8.8] and Chinese [8.5].

Serum leptin levels were also significantly higher in South Asians [11.8] and Aboriginals [11.1] compared to Europeans [9.2] and Chinese [8.3].

BMI and waist circumference were inversely associated with adiponectin in every group except the South Asians.

The increase in HOMA-IR (a measure of insulin resistance) for each given decrease in adiponectin was larger among South Asians and Aboriginals compared to Europeans.

Interestingly, a high glycemic index diet was associated with a larger decrease in adiponectin among South Asians and Aboriginals, and a larger increase in HOMA-IR among South Asians relative to other groups.

This study clearly shows that South Asians have the least favourable adipokine profile of the studied ethnic groups, and like the Aboriginal people, display a greater increase in insulin resistance with decreasing levels of adiponectin.

The reasons for these differences are not clear but we are studying possible mechanisms to explain these findings in South Asians in a “molecular” version of this study.

AMS
Hamilton, Ontario

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Mente A, Razak F, Blankenberg S, Vuksan V, Davis AD, Miller R, Teo K, Gerstein H, Sharma AM, Yusuf S, Anand SS, & for the SHARE, SHARE-AP investigators (2010). Ethnic variation in adiponectin and leptin levels and their association with adiposity and insulin resistance. Diabetes care PMID: 20413520