Development of bone mineral loss in insulin-treated diabetes: a 1 1/2 years follow-up study in sixty patients.

The change in bone mass during 1 1/2 years was determined in a longitudinal study of sixty adult insulin-treated diabetic out-patients. During the study period the mean bone mass decreased by 1.30 +/- 0.28 (SEM)% (P less than 0.001), to a mean value of 91.0 +/- 1.7% of normal (P less than 0.001). The rate of bone loss was significantly higher in patients with 1-6 years of diabetes (n = 29, bone loss: 1.96 +/- 0.32%/1 1/2 years) than in patients with longer duration of the disease (n = 31, bone loss: 0.61 +/- 0.44%/1 1/2 years, P less than 0.02). The endogenous insulin secretion estimated with the glucagon-stimulated serum C-peptide concentration decreased during the observation period in 58.6% of the patients with 1-6 years of diabetes compared to 16.1% among patients with 7-11 years of diabetes (P less than 0.002). The rate of bone mineral loss was almost 3 times higher in the twenty-two patients in whom endogenous insulin secretion had deteriorated (2.12 +/- 0.30%/1 1/2 years) than in the thirty-eight patients without as well as with unchanged or increased insulin secretion (0.78 +/- 0.39%/1 1/2 years, P less than 0.01). In twenty patients with an increased insulin dose during the study period the mean bone mineral loss was 2.05 +/- 0.36%/1 1/2 years compared to a mean bone mineral loss of 0.91 +/- 0.38%/1 1/2 years in the forty patients with unchanged or decreased insulin dosage (P less than 0.05). This longitudinal study further supports the hypothesis that the bone mineral loss in insulin-treated diabetic patients begins with the onset of clinical diabetes and that its development is associated with the deterioration of the beta-cell function and with the increment in insulin dosage. The rate of bone mineral loss is high during the first few years of clinical diabetes, but levels off with increasing duration of the disease.