In this study, we evaluated bone turnover in 35 patients with non- insulin-dependent diabetes mellitus with no complications and in 35 healthy volunteers who formed the control group and whose ages matched those of the patients. We determined serum osteocalcin (OC) and total alkaline phosphatase levels as markers of bone formation, and urinary deoxypyridinoline (DPD) and urinary calcium levels as markers of bone resorption. Statistical comparison of the levels of these markers between sexes in diabetic and control groups revealed that the OC levels were significantly decreased in males and females in the diabetic group compared with those of the control group. No significant difference was observed for other markers. It was found that the OC levels of diabetic subjects were not affected by the type of therapy. No statistically significant difference was found in serum calcium, phosphorus and magnesium levels between the diabetic and the control groups. In our study, the finding that, in spite of the decrease in the OC levels in the diabetic group no difference was observed in DPD levels, was attributed to the fact that only the formation phase was affected in diabetes, while the resorption phase remained unaltered. (C) 1998 Elsevier Science Ireland Ltd, All rights reserved.