Measurement of bone density and turnover was assessed in 20 premenopausal females with Type 1 diabetes mellitus and 27 age-sex-matched controls. Measurement was made of spinal (L2-4) and neck of femur bone density by dual-energy X-ray absorptiometry. L2-4 density was significantly higher in the diabetic patients compared with controls (1.224 +/- 0.021 g cm-2 vs. 1.161 +/- 0.020 g cm-2: p = 0.016). No significant difference was noted between the groups in neck of femur density. Measurement of bone formation was assessed by serum alkaline phosphatase and bone resorption by fasting urinary hydroxyproline/creatinine ratio. Alkaline phosphatase was significantly higher in the diabetic patients (185 +/- 16 Ul-1 vs 135 +/- 10 Ul-1: p < 0.01) as was hydroxyproline/creatinine ratio (0.028 +/- 0.003 vs 0.017 +/- 0.002: p = 0.002). No significant correlation was found between L2-4 density and glycated haemoglobin, duration of diabetes or daily dose of insulin taken. These data suggest that osteopenia is not associated with Type 1 diabetes mellitus; however these patients do have evidence of increased bone turnover and may therefore be at risk of osteoporosis in later life, particularly after the menopause.