Background: Studies have reported a high prevalence of preclinical diastolic dysfunction among patients with diabetes mellitus (DM). However, there have been few studies to evaluate the outcomes of preclinical diastolic dysfunction in DM. The objective of our study is to determine if there is an association between diastolic dysfunction in DM patients and the subsequent development of heart failure (HF). Methods: We retrospectively identified all DM patients with a tissue Doppler assessment of diastolic function within the Olmsted County, MN population from September 2001 through June 2005. Patients with a diagnosis of HF prior to the echocardiogram were excluded as were patients with severe mitral or aortic valve regurgitation. Diastolic dysfunction was defined as a Doppler mitral E/e' ratio ≥ 15 as previously described. The main outcome was the development of HF. Results: Overall, 1924 diabetic patients with a tissue Doppler echocardiographic assessment of diastolic function were identified of which 505 patients (26%) had diastolic dysfunction as defined above. Average time from echocardiogram to HF or latest follow-up was 2.52±1.77 years. Using Cox's proportional hazard modeling we determined that for every 1 unit increase in the mitral E/e' ratio the hazard of HF increases by 4% (HR=1.04, 95% CI=1.02–1.05; p<0.001) and that diastolic dysfunction was associated with the subsequent development of HF (HR=1.76, 95% CI=1.40–2.23; p<0.001) after adjustment for age, sex, body mass index, hypertension, coronary disease, ejection fraction, left atrial volume and deceleration time. Conclusion: This study confirms that preclinical diastolic dysfunction is prevalent in DM patients. More importantly, we demonstrated that an increase in the E/e' ratio in DM patients is associated with the subsequent development of HF independent of hypertension, coronary disease or other echocardiographic parameters. Background: Studies have reported a high prevalence of preclinical diastolic dysfunction among patients with diabetes mellitus (DM). However, there have been few studies to evaluate the outcomes of preclinical diastolic dysfunction in DM. The objective of our study is to determine if there is an association between diastolic dysfunction in DM patients and the subsequent development of heart failure (HF). Methods: We retrospectively identified all DM patients with a tissue Doppler assessment of diastolic function within the Olmsted County, MN population from September 2001 through June 2005. Patients with a diagnosis of HF prior to the echocardiogram were excluded as were patients with severe mitral or aortic valve regurgitation. Diastolic dysfunction was defined as a Doppler mitral E/e' ratio ≥ 15 as previously described. The main outcome was the development of HF. Results: Overall, 1924 diabetic patients with a tissue Doppler echocardiographic assessment of diastolic function were identified of which 505 patients (26%) had diastolic dysfunction as defined above. Average time from echocardiogram to HF or latest follow-up was 2.52±1.77 years. Using Cox's proportional hazard modeling we determined that for every 1 unit increase in the mitral E/e' ratio the hazard of HF increases by 4% (HR=1.04, 95% CI=1.02–1.05; p<0.001) and that diastolic dysfunction was associated with the subsequent development of HF (HR=1.76, 95% CI=1.40–2.23; p<0.001) after adjustment for age, sex, body mass index, hypertension, coronary disease, ejection fraction, left atrial volume and deceleration time. Conclusion: This study confirms that preclinical diastolic dysfunction is prevalent in DM patients. More importantly, we demonstrated that an increase in the E/e' ratio in DM patients is associated with the subsequent development of HF independent of hypertension, coronary disease or other echocardiographic parameters.