Effects of mild diabetes on immature cortical bone.

Abstract

Diabetes mellitus can adversely affect bone, and clinical data show that cortical bone can respond differentially to the systemic effects of diabetes, with distal bones more adversely affected in diabetic osteoarthropathy. To examine the differential effects of diabetic osteoarthropathy on distal and proximal immature bones we examined the morphological and biomechanical characteristics of tibia and second metatarsus of streptozotocin-induced diabetic rats. Female Sprague-Dawley rats (8 weeks) were randomly divided into three groups: control, diabetes, and diabetes with insulin therapy for 10 weeks. The right tibia and metatarsus were tested in three-point bending to failure, and contralateral bones were used for morphological analyses. Length, mid-diaphyseal cross-sectional geometry, and mechanical properties of the experimental tibiae were typically not significantly different from the control. The diabetes with insulin metatarsus was generally no different morphologically and mechanically from control, but the diabetes metatarsus structural properties and medullary cross-sectional area were significantly less than control. The percent of the cortical cross-sectional area accounted for by the periosteal band, however, was significantly greater in the diabetes metatarsus. Results highlight the bone-specific, proximal versus distal alterations that occur with diabetes mellitus. Insulin treatment mitigated the adverse effects that mild, streptozotocin-induced diabetes had on rat cortical bone.