Adiponectin Protein Levels May Predict Type 2 Diabetes

Potential Key to the Obesity-Diabetes Link

High levels of the recently discovered protein adiponectin are strongly correlated with a reduced likelihood of the prediabetic state—impaired glucose metabolism (IGM)—as well as type 2 diabetes, new findings suggest. Added to previous research that showed that obese persons have low levels of adiponectin protein, these results suggest that adiponectin may be key to the pathophysiologic pathway connecting obesity and type 2 diabetes.

The findings come from a new analysis of the Hoorn Study of a subpopulation of 1264 persons who did not have diabetes at baseline (Diabetes Care. 2006; 29:2498-2503). The Hoorn study included white men and women (aged 50-75 years) who were evaluated at baseline for body mass index (BMI), waist-to-hip ratio, fasting glucose, lipids, leptin, and adiponectin.

The 584 men (mean BMI, 25.1-26.6 kg/m²) and 680 women (mean BMI, 25.7-27.3 kg/m²) were divided into quartiles based on baseline adiponectin levels, which ranged from a mean of 5.66 to 20.41 μg/mL in men and from 8.48 to 24.78 μg/mL in women.

At the end of 6.4 years of follow-up, all participants underwent oral glucose tolerance testing to determine the incidence of newly developed diabetes. The 239 participants who had IGM at baseline or who were diagnosed with type 2 diabetes at follow-up were excluded before assessing incident IGM.

Analysis revealed an inverse relationship between adiponectin levels and the risk of diabetes, particularly in women (Figure). Those at the highest quartile of baseline adiponectin quartiles, after adjusting for age and lifestyle factors, were less at risk of developing diabetes than those at the lowest quartile.

Analysis of baseline adiponectin level and the development of IGM during follow-up revealed a similar pattern in women, but not in men, with an odds ratio of 0.90 in men and 0.28 in women for those in the highest adiponectin quartile as compared with the lowest.

Adjusting for markers of abdominal adiposity (ie, waist-to-hip ratio, leptin) changed the odds ratio only slightly, but adjusting for potential mediators (ie, baseline fasting, postload glucose levels) significantly lessened the inverse association in both genders.

“Our results strongly support the hypothesis that adiponectin may play an important role in the pathogenesis of abnormal glucose metabolism,” the authors write. They speculate that a low adiponectin level may allow fat to accumulate in the liver, setting the stage for metabolic disturbances.