Smoking is a strong risk factor for non-vertebral fractures in women with diabetes: The Tromsø Study

Summary: In this longitudinal study of 4,160 postmenopausal women (3,947 without and 213 with self-reported diabetes), smoking was strongly related to fracture risk in those with diabetes. Introduction: Smoking is related to low bone mass and increased risk of fracture risk in postmenopausal women of the general population. The aim of the present longitudinal population-based study was to examine the effect of smoking on the risk of non-vertebral fractures in women ≥55 years of age, with specific focus on its relationship with diabetes. Methods: A total of 4,160 women (3,947 without and 213 with self-reported diabetes) from the municipality of Tromsø, Norway, were followed for a mean of 7.6 years. Measurements of height and weight and questionnaire information concerning smoking and alcohol consumption habits, physical activity, prevalent diseases, and use of medication were collected before the start of follow-up. Non-vertebral fractures were registered during follow-up. Results: A total of 1,015 without and 66 with diabetes sustained a new non-vertebral fracture. Smoking status (never, past, and current) was significantly associated with an increased risk of fracture both in women with and without diabetes (p values for trend 0.02 and <0.001, respectively, after adjustments for age), but in women without diabetes, the relationship was no longer significant after multiple adjustments. There was a strong interaction between smoking status and diabetes on fracture risk (p=0.004). Women with diabetes who were current smokers had a 3.47 (95% CI 1.82-6.62) higher risk of non-vertebral fractures than diabetic women who were never smokers (p value for linear trend=0.001, after multiple adjustments). Conclusion: We conclude that smoking is strongly related to fracture risk in postmenopausal women with self-reported diabetes.