Type 2 diabetes (T2DM), osteoporosis and fracture are increasingly prevalent. Effect of T2DM on fractures and post-fracture outcomes remains unclear. This study examined the effect of T2DM on initial fracture, subsequent fracture and post-fracture mortality risk in elderly individuals in a combined cohort of the Dubbo Osteoporosis Epidemiological Study (DOES) and Canadian Multicentre Osteoporosis study (CaMos).
The study followed 9275 community-dwelling adults (6363 women) aged 60+ years over 13 years (IQR:7-15.1). DOES had fewer participants (39%) but longer follow-up (14 vs 11 years) compared to CaMos. Fractures were radiologically verified. Baseline and incident self-reported T2DM status was confirmed with medication use where available. We analysed T2DM as a time-dependent predictor using Cox’s proportional hazards regression in gender-specific models with adjustment for known confounding factors. First fracture, subsequent fracture and post-fracture mortality were compared between those with and without diabetes.
T2DM was present in 471/2912 (16%) men and 782/6363 (12%) women (including incident T2DM in 159 men and 289 women). Fracture incidence was lower in both men and women with T2DM than those without (11% vs 15% men; 24% vs 29% women, respectively). Femoral neck bone mineral density (FNBMD) was significantly higher in women with T2DM compared to those without T2DM (p <0.01). T2DM was not associated with increased risk of first or subsequent fracture in age-adjusted or after accounting for all potential confounding effects in either women or men (Figure). However, T2DM was associated with increased risk of post-fracture mortality in men (HR 1.95; 95%CI:1.23-3.11) but not in women (1.32; 0.95-1.81).
Women and men with T2DM have similar fracture rates to those without T2DM. After a fracture, mortality in women is similar between T2DM and non-diabetes subjects whereas mortality in men is further increased by T2DM. Fracture risk reduction is therefore important in men and women with T2DM.