This study was undertaken to assess the associations of C-reactive protein (CRP) with incident type-2 diabetes mellitus (T2DM) and to determine the joint effect of obesity and hypertension on them in the large-scale population-based Korean cohort of the Korean Genome and Epidemiology study (KoGES). We included 22,946 men and women from 11 rural communities at baseline (2005-2011). Epidemiological data and blood samples were collected. Incident physician-diagnosed T2DM cases (130 men and 148 women) were self-reported or based on fasting glucose ≥126 mg/dL or HbA1c level ≥6.5% during a median follow-up of 3.0 years (58,916 person-years) between 2007 and 2014. After multivariate adjustment for T2DM risk factors, the hazard ratios for developing T2DM in the highest CRP tertile (T3), compared with the lowest (T1), was 2.80 (1.73-4.52; p for trend <0.0001) in women and 1.67 (1.00-2.45; p for trend 0.02) in men. The associations between CRP and incident T2DM were more prominent among the older group (≥50 years). And CRP and its combination with obesity and hypertension were associated with increased risk of T2DM. In conclusion, we found positive associations between CRP and incident T2DM in a large population-based Korean cohort.