Serum γ-glutamyltransferase and risk of type 2 diabetes mellitus in men and women from the general population

Objectives. To examine gender-specific associations between gamma-glutamyltransferase (GGT) and incident type 2 diabetes mellitus in a representative population-based sample in Germany. Design. Prospective population-based study. Methods. The study was based on 1851 men and 1836 women (aged 25-64 years) who participated in the first Monitoring Trends and Determinants on Cardiovascular Diseases (MONICA) Augsburg Survey 1984/1985, and who were free of diabetes at baseline. Incident cases of type 2 diabetes were assessed using follow-up questionnaires in 1987/1988, 1997/1998 and 2002/2003 and were validated with medical records. Gender-specific hazard ratios (HRs) were estimated from Cox proportional hazard models. Results. A total of 172 cases of incident type 2 diabetes amongst men and 109 amongst women were registered during a mean follow-up period of 14.7 years. In both sexes the risk of type 2 diabetes increased with increasing levels of serum GGT. After multivariable adjustment HRs for incident type 2 diabetes across GGT categories (< 25th, < 50th, < 75th, < 87.5th and >= 87.5th percentiles) were 1.0, 1.81, 2.37, 3.41 and 4.24 (P-value for trend < 0.0001) in men and 1.0, 1.42, 1.48, 1.95 and 2.41 (P-value for trend 0.0179) in women. Obesity appeared to be more strongly associated with type 2 diabetes in women with GGT equal or greater than the median compared to women with GGT below the median. However, in men the association between obesity and type 2 diabetes was almost identical in the two groups. Conclusions. The GGT is an important predictor for incident type 2 diabetes in men and women from the general population.