The prevalence and significance of microalbuminuria in hypertensive patients with impaired fasting glucose (IFG) has received very little attention. A total of 10,320 hypertensive patients who attended primary care centers were enrolled in this study, and the final analysis was done in 7625 patients: 1459 without IFG (plasma glucose <100 mg/dl), 3010 with IFG (plasma glucose > or =100 mg/dl and <126 mg/dl), and 3156 with type 2 diabetes (plasma glucose >126 mg/dl). Microalbuminuria was determined using the Micro Albustix reactive strip from Bayer (high urinary albumin excretion [UAE]: Albumin/creatinine ratio > or =3.4 mg/mmol). The proportion of patients with high UAE was 39.4, 48.3, and 65.6%, respectively, in the three groups (P < 0.01 for the trend). The differences in UAE between the group with IFG and the group with normal fasting glucose persisted after adjustment for age, gender, systolic BP, fasting plasma glucose, and cardiovascular comorbidity (odds ratio 1.74; 95% confidence interval 1.08 to 2.80). Hypertensive patients with IFG and high UAE showed a higher prevalence of ischemic heart disease, cardiac insufficiency, left ventricular hypertrophy, atrial fibrillation, and renal insufficiency than the group with normal UAE. Global prevalence of cardiovascular conditions was 30.4% in the group with high UAE compared with 21.4% in the group with normal UAE (odds ratio 1.60; 95% confidence interval 1.31 to 1.95). It is concluded that almost half of hypertensive patients with IFG have high UAE and a higher prevalence of associated cardiovascular involvement and renal insufficiency.