This paper discusses the adverse effect of statins on the HbA1c levels of diabetic patients. Studies have shown that statins may slightly worsen the HbA1c level. The effects vary depending on the type of statins, the dosage and the duration of therapy. However, it has been confirmed that statin use has benefits that outweigh its harms. Therefore, a diabetic patient should be given advice on the need for appropriate lifestyle changes and the importance of continuing the statins.