Prior studies have suggested associations between type 2 diabetes mellitus (T2DM) and risk of non-Hodgkin lymphoma (NHL) and multiple myeloma (MM), but data on specific histologic subtypes have been limited. This pooled analysis published in the JNCI Cancer Spectrum included 585,114 participants from the Cancer Prevention Study-II Nutrition Cohort, California Teachers’ Study, Health Professionals Follow-up Study, Nurses’ Health Study (NHS), NHSII, and Kaiser Permanente Southern California. 

During a median follow-up of 20 years, 11,478 NHL and 2,783 MM cases were identified. T2DM history was not associated with overall NHL risk. However, T2D was positively associated with diffuse large B-cell lymphoma (DLBCL; HR 1.15, 95% CI 1.04–1.28) and MM (HR 1.20, 95% CI 1.07–1.35). T2DM duration was also positively associated with DLBCL and MM. In contrast, inverse associations were observed for lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (HR 0.45, 95% CI 0.27–0.75), T-cell NHL (HR 0.78, 95% CI 0.62–0.97), and mycosis fungoides/Sezary syndrome (HR 0.67, 95% CI 0.46–0.98).

These findings indicate heterogeneity in lymphoma subtype-specific associations with T2DM. The results suggest potential implications for DLBCL and multiple myeloma (MM) incidence, while unexpected inverse associations warrant further investigation.