Bone and insulin resistance - a literature review

Abstract

Insulin resistance (IR) is defined as a decreased tissue response to insulin-mediated cellular activity. Decreased insulin sensitivity and concomitant hyperinsulinemia are known to play a central role in metabolic disorders associated with obesity, metabolic syndrome (MetS) and type 2 diabetes mellitus (DM). In recent years, more and more research has been focused on the relationship between IR and bone health. In vitro, physiological concentrations of insulin have been shown to increase osteoblast proliferation rate, collagen synthesis, alkaline phosphatase production, and glucose uptake and to inhibit osteoclast activity. This evidence indicates that insulin acts as an anabolic agent on bone. It remains to be discussed whether osteoblasts retain their sensitivity to insulin in states of IR. On the one hand, a large number of clinical studies have established that IR and concomitant hyperinsulinemia are positively associated with bone mineral density (BMD), both in individuals with or without overt DM. On the other hand, a number of researchers have found suppressed bone metabolism and decreased bone volume in an IR state . The data on the effect of IR on bone microarchitectonics and bone strength are also controversial. In relation to these data, it remains unclear whether the net effect of IR is favorable or unfavorable for bone health and fracture risk.