Microalbuminuria (MA) is a well-known risk factor for coronary artery disease (CAD) in diabetics and nondiabetics. It is associated with higher cardiovascular mortality, especially in diabetics. However, there are few data linking angiographic severity of CAD to microalbuminuria. We examined coronary angiograms for extent of severe CAD (luminal narrowing > or = 50%) in patients with type 2 diabetes mellitus (DM) and MA (DM+MA+, n = 101), patients with DM and without MA (DM+MA-, n = 101), patients without DM and with MA (DM-MA+, n = 64), and patients without DM and MA (DM-MA-, n = 64). We also evaluated fasting glucose levels in all patients and glycosylated hemoglobin in diabetics. Patients' mean age in the DM+MA+, DM+MA-, DM-MA+, and DM-MA- groups was similar. Gender distribution across the 4 groups was also not significantly different. There were no significant differences in the prevalence of hypertension, hypercholesterolemia, and current smoking across the 4 groups. The presence of 2- or 3-vessel CAD showed a linear increase from group DM-MA- to group DM+MA+ (p < 0.001). Diabetics with MA had higher fasting glucose and glycosylated hemoglobin levels than diabetics without MA (p < 0.001). Thus, patients with MA have more severe angiographic CAD than those without MA. This relation is independent of other risk factors and is particularly evident in patients with DM.