To identify subjects with diabetes who may be at risk of developing osteoporosis and fractures, we analysed bone mineral density in relation to the biochemical markers of bone turnover, calcium homeostasis and the COL1A1 genotype in a group of premenopausal women with Type I (insulin-dependent) diabetes mellitus (n = 31), Type II (non-insulin dependent) diabetes mellitus (n = 21) and control subjects (n = 20).