Is Diabetes Mellitus An Independent Risk Factor for Incident Venous Thromboembolism (VTE)? a Population-Based Case-Control Study

Introduction: Diabetes mellitus is often cited as a VTE risk factor. However, persons with diabetes are frequently hospitalized for medical illness or undergo surgery, both major VTE risk factors. Thus, the association of VTE with diabetes independent of surgery or hospitalization is uncertain.

Methods: Using longitudinal, population-based Rochester Epidemiology Project resources, we identified all Olmsted County, MN residents who met objective criteria for incident VTE over the 25-year period, 1976–2000 (n=1922), and one to two controls per case, matched on age, gender, Olmsted County residency, and length of medical history (n=2115). For cases and controls, we reviewed their complete medical history in the community for baseline characteristics previously identified as independent VTE risk factors, including clinically-diagnosed diabetes mellitus. We tested diabetes as a potential VTE risk factor both alone and after adjusting for other baseline characteristics, and in the subset of cases with idiopathic VTE, using conditional logistic regression.

Results: Among all cases and controls, 231 (12%) and 199 (9.4%) had diabetes, respectively. Univariately, diabetes was associated with overall VTE (odds ratio [OR]=1.32; 95% CI: 1.07, 1.62; p=0.009). However, after controlling for body mass index (OR=1.04, p<0.001), hospitalization with major surgery (OR=25.2, p<0.001) or hospitalization for medical illness (OR=7.3, p<0.001), active cancer (OR=8.3, p<0.001) and varicose veins (OR=1.3, p=0.003), diabetes was no longer associated with VTE (OR=1.09; 95% CI: 0.85, 1.41; p=0.49). Among 458 idiopathic VTE cases and 518 matched controls, 43 (9.4%) and 46 (8.9%) had diabetes, respectively. Diabetes was not associated with idiopathic VTE (OR=1.07, 95% CI: 0.69, 1.67; p=0.76).

Conclusions: Diabetes mellitus is not an independent risk factor for overall or idiopathic incident VTE.