Background: Type 2 diabetes mellitus (T2DM) is a progressive lifelong disease with long term dangerous cardiovascular complications. microRNA-499 (miRNA-499) is a muscle-specific miRNA and is highly expressed in normal heart. Objective: This case control study was designed to evaluate miRNA-499 serum gene expression levels in Egyptian T2DM patients in comparison with normal healthy volunteers and to explore its relationship with coronary heart disease (CHD). Methods: This study was performed on 180 individuals enrolled from Kasr Al-Ainy Hospital. They were divided into three groups; 60 T2DM patients with CHD, 60 T2DM patients without any complication and 60 healthy volunteers. Fasting blood glucose, HbA1c and complete lipid profile were assessed. miRNA-499 gene expression was evaluated by quantitative Real Time PCR. Receiver Operating Characteristics (ROC) curve of miRNA-499 serum gene expression was performed to study the ability of miRNA-499 gene expression to discriminate between the studied groups. Results: miRNA-499 gene expression was downregulated in both diabetic groups (p>0.001**) than control group and in diabetic group with CHD complication than diabetic group without (p>0.05**). ROC curve revealed that miRNA-499 gene expression discriminated between diabetic patients and controls with sensitivity 90% and specificity 96.6%. miRNA-499 gene expression discriminated also between diabetic patients with and without CHD complication with sensitivity 73% and specificity 70%. miRNA-499 downregulation was related to elevated T2DM and its CHD complication risks. Conclusion: miRNA-499 could be a beneficial biomarker for T2DM and its CHD complication and could discriminate between diabetic patients with and without CHD complication and normal individuals.