Discrepancies in type of first major osteoporotic fracture and anti-osteoporotic therapy in elderly people with type 2 diabetes mellitus: A retrospective Danish cohort study.

OBJECTIVE: Subjects with diabetes mellitus have an increased risk of fractures. We aimed to identify discrepancies in the first type of major osteoporotic fracture (MOF) and anti-osteoporotic therapy between subjects with type 2 diabetes (T2D) and subjects without diabetes. Methods and research design. We conducted a retrospective national cohort study by access to all discharge diagnoses (ICD-10 system) and redeemed drug prescriptions (ATC classification system). We included all subjects alive and Danish citizens in 2010 and identified subjects with T2D diagnosed after the age of 50 between 1998 and 2018. Only subjects with a MOF after the index date were included in the main analysis. The type of MOF was identified by diagnosis codes and categorized into Humerus, Forearm, Spine, and Hip. Multinomial logistic regression modeling was used to assess the predicted probability changes in MOF type between T2D and control subjects. Data on first anti-osteoporotic therapy after the MOF was assessed by redeemed drug prescriptions. Mortality and time to therapy after the MOF were evaluated by cox proportional hazards.

RESULT: We included 26,588 subjects with T2D and 97,982 subjects without diabetes. The mean age was age 69.33 (±10.34) for T2D and 69.85 (±10.19) for control subjects. The cohort was primarily females (67 %). Subjects with T2D had a higher probability of hip (3.98 % [95 % CI 3.29; 4.67]) and humerus (2.82 % [95 % CI 2.17; 3.46]) fractures as the first MOF compared to control subjects. However, the probability of forearm fractures as the first MOF was 6.77 % (95 % CI 6.08; 7.46) lower among subjects with T2D. The multiple adjusted hazard ratio for anti-osteoporotic treatment after the first MOF was 0.80 (95 % CI 0.77; 0.88) for T2D compared to controls among treatment-naïve subjects.

CONCLUSION: Forearm fractures were the most frequent type of MOF and were more prevalent in control subjects. Subjects with T2D had a significantly higher probability of hip and humerus fractures as the first MOF but had a 20 % lower chance of anti-osteoporotic treatment afterwards.