Introduction: Several studies have shown that ventricular dysfunction is increased in individuals with diabetes. Insulin resistance (IR) may precede type 2 diabetes, and is a pathogenic factor for it. Furthermore, IR has been shown to be an independent predictor of cardiovascular disease in diabetes. Given that glucose intolerance and IR precede the development of overt diabetes, these factors would be associated with abnormal myocardial performance. Aim of the Work: To evaluate the state of left ventricular structure and function in prediabetic adults in relation with IR. Patients and Methods: A case–control study was performed. One hundred and twenty-one consecutive adults with prediabetes were enrolled for the study. Forty-two of the adults had IR (group A) and 79 had insulin sensitivity (group B). Forty-three healthy (with normal blood glucose) adults matched for age and gender were considered as a control group. All groups were subjected to full medical history and clinical examination and biochemical and echocardiographic studies. Results: There were no statistically significant differences between the insulin-sensitive prediabetic group and the control group in all parameters of left ventricular structure and systolic and diastolic functions. Significant differences were observed between group A and control group in the parameters of left ventricular diastolic function (both isovolumetric relaxation time and E/A ratio). Regarding correlation between the parameters of diastolic function and different variables of IR prediabetic group, there was a statistically significant coefficient correlation with HOMA IR, waist circumference and triglycerides. No correlation was observed with fasting glucose, Hb A1c, body mass index, blood pressure (BP) and total lipids. Conclusion: In prediabetic adults, IR is associated with impaired left ventricular diastolic function, and this association appears to be independent of BP, ventricular geometry, glucose tolerance status, total plasma lipids and obesity.