Impact of peripheral neuropathy on bone density in patients with type 1 diabetes.
OBJECTIVE: To investigate whether peripheral neuropathy (PN), as part of the microangiopathic complex, affects bone mineral density (BMD) of the peripheral or the axial skeleton in patients with type 1 diabetes. RESEARCH DESIGN AND METHODS: Three study groups were examined. Group 1 comprised 21 males with type 1 diabetes and severe PN with a mean (range) duration of diabetes of 28 (9-59) years and an HbA1c of 8.2% (6.3-10.4). Group 2 comprised 21 male type 1 diabetic patients with absent or mild PN matched to patients of group 1 regarding age, weight, and duration of diabetes. Group 3 comprised 21 control subjects. BMD was measured by dual-energy x-ray absorptiometry (DEXA) and by quantitative ultrasound of the calcaneus. PN was determined by biothesiometry. Levels of physical activity were assessed through guided questionnaires. RESULTS: In group 1, BMD was significantly reduced at all measured sites, compared with an expected Z score of 0 (spine, -1.01 +/- 0.34; femur, -0.94 +/- 0.25; forearm, -1.10 +/- 0.36). To a lesser extent, but still significantly, group 2 also showed reduced BMD values (spine, -0.60 +/- 0.26; femur, -0.55 +/- 0.25; forearm, -1.05 +/- 0.36), whereas group 3 had normal BMD values (-0.23 +/- 0.25, -0.10 +/- 0.21, -0.07 +/- 0.25, respectively). Group 1 had lower mean BMD levels than group 2 and group 3 at all measured sites, but a significant difference was found only between groups 1 and 3 at the site of the femur (analysis of variance, P < 0.05). Broadband ultrasound attenuation (BUA) of the calcaneus was significantly reduced in group 1 compared with groups 2 and 3 (108 +/- 3 vs. 115 +/- 2 and 115 +/- 2). Significant correlations between all DEXA measurements and BUA were demonstrated in both groups 1 and 2 (r values between 0.54 and 0.75). No significant differences in physical activity levels or body composition were demonstrated between the two patient groups. CONCLUSIONS: The present results suggest that in patients with type 1 diabetes, PN may be an independent risk factor for reduced BMD in the affected limbs as well as in the skeleton in general.