Increased incidence of non-Hodgkin lymphoma, leukemia, and myeloma in patients with diabetes mellitus type 2: a meta-analysis of observational studies.

Hematologic malignancies are a heterogeneous group of conditions with an unclear etiology. We hypothesized that diabetes mellitus type 2 is associated with increased risk of developing lymphoma, leukemia, and myeloma. A literature search identified 26 studies (13 case-control and 13 cohort studies) evaluating such an association. Outcome was calculated as the odds ratio (OR) using a random effects model. Heterogeneity and publication bias were evaluated using the I(2) index and the trim-and-fill analysis, respectively. Quality was assessed using the Newcastle-Ottawa scale. The OR for non-Hodgkin lymphoma was increased at 1.22 (95% confidence interval [CI], 1.07-1.39; P < .01) but the OR for Hodgkin lymphoma was not. There was an increased OR for peripheral T-cell lymphoma (OR = 2.42, 95% CI, 1.24-4.72; P = .009) but not for other non-Hodgkin lymphoma subtypes. The OR for leukemia was 1.22 (95% CI, 1.03-1.44; P = .02) and the OR for myeloma was 1.22 (95% CI, 0.98-1.53; P = .08). Although diabetes mellitus type 2 seems to increase the risk of developing lymphoma, leukemia, and myeloma, future studies should focus on evaluating other potential confounders such as obesity, dietary habits, physical activity, and/or antidiabetic therapy.