Abstract P074: Caffeine Intake May be Associated with a Lower Risk of Type 2 Diabetes in the Physicians’ Health Study and Meta-Analysis

Objectives: Short-term metabolic studies have shown that caffeine improves insulin-sensitivity. However, epidemiological studies evaluating the relationship of caffeine intake with risk of type 2 diabetes (DM) have shown inconsistent results. We examined whether caffeine intake is associated with the risk of DM in the Physicians’ Health Study and supplemented the results with a meta-analysis. Methods: We prospectively analyzed data on 18,432 PHS participants that were free of DM at baseline (1997-2001). Caffeine intake was assessed using a food-frequency questionnaire. Incident DM was ascertained via annual follow-up questionnaires and validated in a subsample by review of medical records. We used Cox proportional hazards models to estimate the HR and 95% CI of DM. Meta-analysis was conducted through a systematic literature search using PubMed and EMBASE. A random-effect model was used and between-studies heterogeneity was estimated with I 2 . Results: In the PHS, mean age at baseline was 66.4 ± 9.3 years, and 1,137 men (6.2%) developed DM during mean follow up of 9.2 years. In a multivariable model adjusted for conventional risk factors of DM, HRs (95% CI) for DM were 1.0 (ref), 1.08 (0.90-1.29), 1.03 (0.85-1.24), 0.98 (0.81-1.18), and 0.86 (0.70-1.04) across consecutive quintiles of caffeine intake (p for linear trend= 0.69). Meta-analysis included 6 studies consisted of 7 separate cohorts comprising 275,971 individuals and 10,048 cases of incident DM. The pooled odds ratio (95% CI) for DM was 0.79 (0.68-0.93) when the highest caffeine intake was compared to the lowest group in random effects model (I 2 =75%). Conclusion: While only the highest category of caffeine intake was associated with a modest and non-significant association with DM in the PHS, results from the meta-analysis were consistent with a lower risk of DM.