NEW YORK (Reuters Health) - Hepatitis C virus (HCV) infection can directly cause insulin resistance, which commonly leads to diabetes, Japanese researchers have found.

HCV infection has been linked to type 2 diabetes, the authors explain, but a definite cause-and-effect relationship has not been established. To investigate, Dr. Kazuhiko Koike, and colleagues from University of Tokyo, studied the development of diabetes using mice that had been bred to carry the core gene of HCV.

Excessive insulin levels were apparent in the mice "as early as 1 month old," the authors report in the medical journal Gastroenterology. Insulin resistance was observed by the age of 2 months.

Administering of glucose to these mice led to only mild glucose intolerance, but when they were fed a high-fat diet they developed overt diabetes.

The authors conclude, "These results indicate a direct involvement of HCV per se in the pathogenesis of diabetes in patients with HCV infection and provide a molecular basis for insulin resistance in such a condition."

This research "makes an important contribution to putting the HCV-diabetes association on a mechanistic footing, thus elevating it from a curious association to an important disease process," write Dr. Steven A. Weinman and Dr. L. Maria Belalcazar from University of Texas Medical Branch, Galveston, in a related editorial.

SOURCE: Gastroenterology, March 2004.