Comparison of plasma adiponectin levels in New Zealand Maori and Caucasian individuals.

AIMS

Adiponectin is an adipocytokine with insulin-sensitising and anti-atherosclerotic effects. Low plasma adiponectin levels are known to predispose to the development of Type 2 diabetes mellitus. Given the increased prevalence of Type 2 diabetes in the Maori population in New Zealand, we carried out a study to compare plasma adiponectin levels between non-diabetic Maori and Caucasian subjects.

METHODS

Plasma adiponectin levels were measured in 111 pairs of non-diabetic Maori and Caucasian individuals, matched for gender, age (+/-6 years), body mass index (+/-4 kg/m2), waist circumference (+/-8 cm), and presence or absence of insulin resistance. Other data collected included anthropometric measurements, indices of glycaemic control and insulin sensitivity and plasma lipid profile. The data were analysed using paired t tests, Wilcoxon signed rank tests and correlation, and linear regression analyses.

RESULTS

Statistical analysis showed the two ethnic groups were well matched with the exception of smoking habits, intercurrent medications, and clinically insignificant differences in HbA1C and total cholesterol levels. Mean plasma adiponectin levels were significantly lower in the Maori group compared with the Caucasian group (7.32+/-SD 4.02 mcg/ml vs 8.32+/-SD 4.15 mcg/ml; p=0.03). The prevalence of abnormally low plasma adiponectin levels (less than or equal to 4.0 mcg/ml) was two times higher in Maori than in Caucasians. The difference in mean plasma adiponectin levels of 1.0 mcg/ml between the two groups was relatively small and less than the normal biological variability for adiponectin measured in our laboratory. In both ethnic groups, there was a significant correlation between plasma adiponectin levels and gender and characteristics of the metabolic syndrome, but not with age, percentage body fat, or smoking habits.

DISCUSSION

These results indicate that Maori people tend to have lower plasma adiponectin levels than Caucasian people of similar age, body shape, and insulin sensitivity. The reason(s) for this ethnic difference remain unclear, but may be related to differences in body composition or genetic control of adiponectin synthesis. Prospective studies are required to determine the etiological importance of these low adiponectin levels in the Maori population.