Suggestion of a deficient osteoblastic function in diabetes mellitus: the possible cause of osteopenia in diabetics.

The mechanism underlying diabetic osteopenia is still unclear and may involve osteoblastic activity and/or the deficit of insulin's anabolic action. Bone gla protein (BGP) is synthesized by the osteoblast and its synthesis increases with 1,25(OH)2D3 and fluoride. Because 1,25(OH)2D3 also stimulates insulin secretion, sodium fluoride administration can be used to investigate deficient osteoblastic activity in diabetics, as reflected by BGP levels. BGP was determined before and after administering sodium fluoride at a dosage of 50 mg/day/15 days to three groups: 14 patients with insulin-dependent diabetes, 16 diabetics on oral antidiabetic treatment, and 25 controls, all of similar age, sex, and characteristics. Basal BGP values (mean +/- SD) were low in diabetics on insulin treatment (4.3 +/- 1.1 ng/ml) and in diabetics on oral antidiabetics (5.8 +/- 1.2 ng/ml) as compared with controls (6.5 +/- 0.7 ng/ml) (P less than 0.001 and less than 0.05, respectively). After giving fluoride, BGP values did not change in the two diabetic groups but did vary in controls (8.1 +/- 0.6 ng/ml, P less than 0.001). These results suggest that deficient osteoblast function could be responsible for osteopenia in diabetics.