Left ventricular (LV) global longitudinal strain (GLS) can detect subclinical myocardial systolic dysfunction in individuals with diabetes. The present study investigates the clinical usefulness and incremental net benefit of identifying subclinical myocardial systolic dysfunction in individuals with diabetes. A cohort of 397 type 2 diabetic individuals was followed up for the occurrence of all-cause mortality. Clinical and echocardiographic data of diabetic patients were assessed retrospectively. LV GLS was evaluated on transthoracic echocardiography using speckle tracking imaging. Subclinical LV systolic dysfunction was defined as LV GLS > −17.0% from 104 healthy volunteers recruited from the community. A total of 178 (44.8%) diabetic individuals had evidence of subclinical LV systolic dysfunction and 46 (11.6%) died during follow-up. The presence of subclinical LV systolic dysfunction was independently associated with all-cause mortality on follow-up (hazard ratio [HR] 2.83, 95% confidence interval [CI] 1.40 to 5.71, p = 0.004). Diabetic individuals without subclinical LV systolic dysfunction had similar survival as the general population (standardized mortality ratio 0.94, 95% CI 0.52 to 1.58). Decision curve analysis showed identification of subclinical LV systolic dysfunction and quantification of LV GLS provided an incremental net clinical benefit at risk stratifying patients for risk of death at 5 years. In conclusion, subclinical LV systolic dysfunction is independently associated with all-cause mortality in diabetic patients. Decision curve analyses suggest use of LV GLS and identification of subclinical LV systolic dysfunction is clinically useful, and provided incremental net clinical benefit for diabetic individuals.