['Blood pressure control can reduce the risk of coronary heart disease (CHD) among diabetic patients; however, it is not known whether the lowest risk of CHD is among diabetic patients with the lowest blood pressure level.', 'We performed a prospective cohort study (2000-2009) on diabetic patients including 17,536 African Americans and 12,618 whites. Cox proportional hazards regression models were used to estimate the association of blood pressure with CHD risk.', 'During a mean follow-up of 6.0 years, 7,260 CHD incident cases were identified. The multivariable-adjusted hazard ratios of CHD associated with different levels of systolic/diastolic blood pressure at baseline (<110/65, 110-119/65-69, 120-129/70-80, and 130-139/80-90 mmHg [reference group]; 140-159/90-100; and ≥160/100 mmHg) were 1.73, 1.16, 1.04, 1.00, 1.06, and 1.11 (P trend<0.001), respectively, for African American diabetic patients, and 1.60, 1.27, 1.08, 1.00, 0.95, and 0.99 (P trend<0.001) for white diabetic patients, respectively. A U-shaped association of isolated systolic and diastolic blood pressure at baseline as well as blood pressure during follow-up with CHD risk was observed among both African American and white diabetic patients (all Ptrend<0.001). The U-shaped association was present in the younger age-group (30-49 years), and this U-shaped association changed to an inverse association in the older age-group (≥60 years).'] Does aggressive blood pressure control increase coronary heart disease risk among diabetic patients?