Relative fracture risk in patients with diabetes mellitus, and the impact of insulin and oral antidiabetic medication on relative fracture risk

Aims/hypothesis: We studied the association between fractures and type 1 and type 2 diabetes mellitus. Methods: In this case-control study, all subjects diagnosed with a fracture (n=124,655) in Denmark served as cases, and for each case three control subjects (n=373,962) matched for sex and age were retrieved from the general population. Results: Type 1 and type 2 diabetes were associated with an increased risk (1) of any fracture (odds ratio [OR]=1.3, 95% CI: 1.2-1.5 for type 1 diabetes and 1.2, 95% CI: 1.1-1.3 for type 2 diabetes after adjustment for confounders) and (2) of hip fractures (OR=1.7, 95% CI: 1.3-2.2 for type 1 diabetes, and 1.4, 95% CI: 1.2-1.6 for type 2 diabetes). Furthermore, type 2 diabetes was associated with a significant increase in forearm fractures (OR=1.2, 95% CI: 1.0-1.5), and type 1 diabetes was associated with an increased risk of spine fractures (OR=2.5, 95% CI: 1.3-4.6), whereas type 2 diabetes was not. Use of metformin and sulphonylureas was associated with a significantly decreased risk of any fracture, whereas a nonsignificant trend towards decreased risk of any fracture was associated with the use of insulin. Except for a decrease in hip fractures with use of sulphonylureas, no change in fracture risk in the hip, spine or forearm was associated with the use of insulin or oral antidiabetic drugs. Conclusions/interpretation: Type 1 and type 2 diabetes are associated with an increased risk of any fracture and hip fractures. The use of drugs to control diabetes may reduce the association between diabetes and fractures.