Intensive Insulin Therapy and Bone Mineral Density in Type 1 Diabetes Mellitus: A Prospective Study

Abstract:

To determine the effect of metabolic control on bone mineral density (BMD) in type 1 diabetes mellitus (type 1 DM), we studied BMD (by dual-energy X-ray energy absorptiometry) and bone remodeling parameters in 62 patients with type 1 DM both before and 7 years after commencement of intensive insulin therapy. Overall outcomes after the 7-year treatment included the stabilization of BMD at all sites, as well as a significant decrease in tartrate-resistant acid phosphatase (TRAP) (4.302 ± 2.62 vs 2.65 ± 0.97 IU/l; p = 0.0001) and increase in intact parathyroid hormone (PTHi) (28.05 ± 15.7 vs 39.78 ± 22.41 ng/l; p = 0.005). Presence of diabetic retinopathy (RTP) versus its absence (non-RTP) was associated with lower BMD in femoral neck (FN) (0.831 ± 0.142 vs 0.756 ± 0.153 mg/cm²; p = 0.03) and Ward’s triangle (WT) (0.736 ± 0.165 vs 0.632 ± 0.172 mg/cm²; p = 0.03), and with a lower T-score in FN (–0.93 ± 1.34 vs –1.70 ± 1.46; p = 0.04) and WT (–0.72 ± 1.42 vs –1.540 ± 1.55; p = 0.04) and Z-score in FN (–0.591 ± 1.23 vs –1.132 ± 1.46; p = 0.01). The percentage of patients with osteopenia or osteoporosis in the RTP group was significantly higher than in the non-RTP group (72% vs 53%, p = 0.05; RR= 3.2) and the glycosylated hemoglobin (HbA1c) levels of the RTP group were also higher (8.53 ± 1.6% vs 7.1 ± 1.1%; p = 0.05). The improvement in metabolic control, increase in body mass index and decrease in resorption parameters could contribute to the stabilization of bone mass in type 1 DM but the presence of retinopathy is a critical factor in the progression of diabetic osteopenia.