Fracture patterns in adult onset type 1 diabetes and associated risk factors – A nationwide cohort study

OBJECTIVE: This study aimed to determine the hazard ratios (HR) for various fracture sites and identify associated risk factors in a cohort of relatively healthy adult people with newly diagnosed type 1 diabetes (T1D). METHODS: The study utilized data from the UK Clinical Practice Research Datalink GOLD (1987-2017). Participants included people aged 20 and above with a T1D diagnosis code (n = 3281) and a new prescription for insulin. Controls without diabetes were matched based on sex, year of birth, and practice. Cox regression analysis was conducted to estimate HRs for any fracture, major osteoporotic fractures (MOFs), and peripheral fractures (lower-arm and lower-leg) in people with T1D compared to controls. Risk factors for T1D were examined and included sex, age, diabetic complications, medication usage, Charlson comorbidity index (CCI), hypoglycemia, previous fractures, falls, and alcohol consumption. Furthermore, T1D was stratified by duration of disease and presence of microvascular complications. RESULTS: The proportion of any fracture was higher in T1D (10.8 %) than controls (7.3). Fully adjusted HRs for any fracture (HR: 1.43, CI95%: 1.17-1.74), MOFs (HR: 1.46, CI95%: 1.04-2.05), and lower-leg fractures (HR: 1.37, CI95%: 1.01-1.85) were statistically significantly increased in people with T1D compared to controls. The primary risk factor across all fracture sites in T1D was a previous fracture. Additional risk factors at different sites included previous falls (HR: 1.64, CI95%: 1.17-2.31), antidepressant use (HR: 1.34, CI95%: 1.02-1.76), and anxiolytic use (HR: 1.54, CI95%: 1.08-2.29) for any fracture; being female (HR: 1.65, CI95%: 1.14-2.38) for MOFs; the presence of retinopathy (HR: 1.47, CI95%: 1.02-2.11) and previous falls (HR: 2.04, CI95%: 1.16-3.59) for lower-arm and lower-leg fractures, respectively. Lipid-lowering medication use decreased the risk of MOFs (HR: 0.66, CI95%: 0.44-0.99). Stratification of T1D by disease duration showed that the relative risk of any fracture in T1D did not increase with longer diabetes duration (0-4 years: HR: 1.52, CI95%: 1.23-1.87; 5-9 years: HR: 1.30, CI95%: 0.99-1.71; <10 years: HR: 1.07, CI95%: 0.74-1.55). Similar patterns were observed for other fracture sites. Moreover, the occurrence of microvascular complications in T1D was linked to a heightened risk of fractures in comparison to controls. However, when considering the T1D cohort independently, the association was not statistically significant. CONCLUSION: In a cohort of relatively healthy and newly diagnosed people with T1D HRs for any fracture, MOFs, and lower-leg fractures compared to controls were increased. A previous fracture was the most consistent risk factor for a subsequent fracture, whereas retinopathy was the only diabetes related one. We postulate a potential initial fracture risk, succeeded by a subsequent risk reduction, which might potentially increase in later years due to the accumulation of complications and other factors.