Summary

Obesity increases the risk of type 2 diabetes. But not all obese individuals develop the condition and there must be other factors involved. A new study shows that fetuin-A, a protein secreted by the liver, may also play a role. Those with higher levels of fetuin-A were more likely to develop diabetes.

Introduction

There is increasing concern that type 2 diabetes is reaching epidemic proportions with obesity being a major contributor. There are also genetic factors involved in diabetes risk but it is not really understood why some people develop diabetes and some do not. Fetuin-A is a protein produced by the liver which has previously been linked to insulin resistance. However, it is not known if it also plays a role in the development of type 2 diabetes.

What was done

Researchers at the University of California, San Diego, and elsewhere, measured baseline fetuin-A levels among participants in the Health, Aging and Body Composition (Health ABC) Study who were free of diabetes at the start. The 406 participants were well-functioning men and women aged between 70 and 79 who were followed up for six years to see how many developed type 2 diabetes.

What was found

Diabetes developed in 135 of the participants during follow-up. Analysis revealed an increase in the incidence of diabetes with increased fetuin-A levels. The third of the group with the highest levels turned out to have twice the incidence of diabetes compared to the third with the lowest levels. The association of fetuin-A with diabetes risk was independent of other risk factors except for abdominal fat. And even when this was controlled for, the relationship remained.

What this study means

This is the first time fetuin-A has been linked to type 2 diabetes, although it has previously been linked to insulin resistance. The findings suggest that fetuin-A plays a part in glucose regulation in humans; it is already known to bind to insulin receptors which means it can block the normal action of insulin. The researchers suggest that interfering with the interaction between fetuin-A and insulin receptors might be a new therapeutic approach to dealing with insulin resistance and diabetes. Further research is needed to see if these findings on the link between fetuin-A and diabetes risk generalize to middle-aged populations which have the highest incidence of the disorder.