The aim of the study was to compare bone mineral density (BMD) and bone turnover in pre- and postmenopausal women with insulin-dependent diabetes mellitus (IDDM), non-insulin-dependent diabetes mellitus (NIDDM) and normal reference women. In a cross-sectional study 31 and 11 premenopausal and 22 and 21 postmenopausal IDDM and NIDDM patients, respectively, were recruited from an outpatient clinic. BMD in the forearm, spine, femur and total body and biochemical markers of bone turnover were measured and compared with reference values obtained from measurements of normal healthy pre- and postmenopausal women. Postmenopausally, but not premenopausally, IDDM patients had lower BMD values than NIDDM patients. Postmenopausal NIDDM patients had higher BMD value than normal women. The differences in BMD between IDDM and NIDDM patients could be explained statistically by differences in body weight between the NIDMM (obese) and IDDM (lean) women. Markers of bone turnover were significantly higher postmenopausally than premenopausally in both IDDM and NIDDM patients. Osteocalcin was significantly lower in postmenopausal NIDDM compared with postmenopausal IDDM patients and reference values. Otherwise there were no differences in the markers of bone turnover between NIDDM and IDDM patients. In conclusion, postmenopausal IDDM patients have a relatively decreased BMD, whereas NIDDM patients seem to be relatively protected from postmenopausal bone loss.