Fracture Risk in Women with Dysglycaemia: Assessing Effects of Baseline and Time-Varying Risk Factors

Although individuals with diabetes appear to have a higher fracture risk compared to those without diabetes, fracture risk in impaired fasting glucose (IFG) has not been thoroughly explored. This study determined associations between glycaemia status and fracture risk. Women (n = 575, aged 50 + years) enrolled in the Geelong Osteoporosis Study, were followed from baseline (1993–1997), to date of first fracture, death or December 31, 2010, whichever occurred first (median 13.7 years, IQR 7.4–14.8). Hazard ratios (HRs) for any fracture (excluding fingers, toes, skull/face), as well as major osteoporotic fracture (MOF, clinical spine, hip, proximal humerus, wrist), in diabetes (n = 69), IFG (n = 250) and normoglycaemia (n = 256), were calculated using a Cox proportional hazards model. Normoglycaemia was set as the reference category. A Cox proportional hazards model with time-varying covariates was also used to assess change in baseline risk factors at the 10-year follow-up visit (2004–2008). During follow-up (6433 person-years), 162 women sustained any fracture and 104 had a MOF. Unadjusted fracture risk was higher in diabetes (HR 1.64; 95% CI 1.02–2.63) compared to normoglycaemia, but IFG and normoglycaemia had similar risk (HR 1.06; 95% CI 0.76–1.47). Age- and BMD-adjusted any-fracture risk in diabetes compared to normoglycaemia was greater (HR 1.59; 95% CI 0.98–2.58); IFG was similar to normoglycaemia (HR 1.01; 95% CI 0.72–1.41). For MOF, unadjusted and age- and BMD-adjusted fracture risk in IFG was similar to normoglycaemia HR 1.02; 95% CI 0.74–1.40 and HR 0.95; 95% CI 0.69–1.32, respectively, but diabetes was higher compared to normoglycaemia (unadjusted HR 1.64; 95% CI 1.04–2.60; adjusted HR 1.57; 95% CI 0.98–2.51). In the time-varying model, there was no difference between IFG in either the unadjusted or adjusted models, for both any fracture and MOF (p > 0.05). For diabetes, there was a significant difference between normoglycaemia in the adjusted model for any fracture (p = 0.046), but not for MOF (p = 0.103). An increased risk of fracture for women with diabetes was observed after accounting for time-varying risk factors. There was no difference in fracture risk detected for women with IFG.