OBJECTIVE: We assessed the impact of diabetes mellitus on survival in South East Asian patients with congestive heart failure. METHODS: 1668 consecutive patients with chronic heart failure (age 65+/-13 years, ejection fraction 28+/-12%, 67% male) were followed up for 36+/-12 months. 837 patients (50.2%) were diabetic and 1076 patients (65%) had ischemic cardiomyopathy. Primary outcome measure was all-cause mortality. Secondary outcome measures were heart failure readmission and the composite end-point. RESULTS: There were 223 (13.4%) deaths and 112 (7%) heart failure readmissions. Ischemic cardiomyopathy, renal failure, hypertension, cerebrovascular disease, peripheral vascular disease, and hyperlipidemia were more prevalent in diabetics (all p<0.01). All-cause mortality (17.3% vs 9.4%), heart failure readmission (8.1% vs 5.3%) and the composite end-point (21.9% vs 12.6%) occurred more frequently in diabetics (all p<0.05). Diabetes was an independent predictor of all-cause mortality (OR=1.70, p=0.01), as were ischemic cardiomyopathy (OR=1.85, p=0.01), hypertension (OR=1.78, p=0.01), GFR (OR=0.98, p<0.01), and beta-blocker use (OR=0.55, p<0.01). CONCLUSIONS: In spite of advances in heart failure treatment, the presence of diabetes mellitus significantly worsens survival in South East Asian patients with congestive heart failure.