Incident early- and later-onset type 2 diabetes and risk of early- and later-onset cancer: prospective cohort study

<p> </p> <p><strong>Objective</strong></p> <p>We evaluated prospectively the association between incident early- (diagnosed under the age of 40 years) and later-onset type 2 diabetes, and early- (diagnosed before age 50) and later-onset cancer risk.</p> <p><strong>Research Design and Methods</strong></p> <p>We prospectively followed 228,073 eligible participants in the Nurses’ Health Studies for up to 38 years. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox models.</p> <p><strong>Results</strong></p> <p>We documented 18,290 type 2 diabetes, 6,520 early-onset cancer, and 36,907 later-onset cancer cases during follow-up. In fully-adjusted analyses, early-onset type 2 diabetes was associated with increased risk of early-onset total cancer (HR, 95%CI was 1.47, 1.06-2.04), diabetes-related cancer (2.11, 1.38-3.23), and obesity-related cancer (1.75, 1.08-2.82), and the risk elevations were restricted to those with BMI at age 18 of ≥21 kg/m2 (total cancer: 1.75, 1.20-2.56; diabetes-related cancer: 2.43, 1.50-3.94; obesity-related cancer: 1.84, 1.05-3.22). Early-onset type 2 diabetes was associated with higher risk of later-onset diabetes-related and obesity-related cancer specifically among individuals with higher BMI at age 18. Later-onset type 2 diabetes was associated with higher risk of later-onset total cancer (1.15, 1.11-1.20), diabetes-related cancer (1.17, 1.12-1.22), and obesity-related cancer (1.18, 1.13-1.24). In analyses based on refined timing, the HRs attenuated substantially with aging.</p> <p><strong>Conclusions</strong></p> <p>Incident early-onset type 2 diabetes was associated with increased risk of early-onset total cancer, and diabetes- and obesity-related cancer, especially in those with higher BMI at age 18. The impact of early-onset type 2 diabetes on cancer risk may be inherently stronger than that of later-onset type 2 diabetes.</p>