We tested whether determination of the ACE insertion/deletion polymorphism is useful for renal and cardiovascular prognoses of type 2 diabetic subjects.The French participants (3,126 of 4,912) in the Non-Insulin-Dependent Diabetes, Hypertension, Microalbuminuria or Proteinuria, Cardiovascular Events, and Ramipril (DIABHYCAR) trial were studied for their prognosis over 4 years according to their ACE insertion/deletion polymorphism. We used two cohorts of French type 2 diabetic patients for replication: a 3-year follow-up study (n = 917; Survie, Diabete de type 2 et Genetique [SURDIAGENE] study) and a case-control study on diabetic nephropathy (n = 1,277; Diabete de type 2, Nephropathie et Genetique [DIAB2NEPHROGENE] study). We investigated the effect of the insertion/deletion polymorphism on the primary outcome in the DIABHYCAR trial (defined as the first of the following events to occur: cardiovascular death, nonfatal myocardial infarction, stroke, heart failure leading to hospital admission, or end-stage renal failure) and its components.In DIABHYCAR, the primary outcome and most of its components were not affected by the ACE insertion/deletion genotype. Only renal outcome was favored by the I allele (P = 0.03). The risk of myocardial infarction was not affected by ACE genotype, but the probability of fatal outcome increased with the number of D alleles (P < 0.03). In SURDIAGENE, the association between the ACE I allele and renal outcome was not replicated. In DIAB2NEPHROGENE, no association was found with nephropathy.We were not able to demonstrate the manifest usefulness of the ACE insertion/deletion polymorphism for the prognosis of type 2 diabetic subjects.