Statins have impacts on the metabolism of glucose that might influence the progress of diabetes in non-diabetics or affect glycemic control in patients with existing diabetes. Experimental proof has been contradictory about whether some statins display beneficial properties while others indicate harmful impressions. Some systematic reviews of statins had stated conflicting findings on the concern of glucose metabolism. The current study investigates the published systematic reviews and meta-analyses to combine their results and give a clear situation regarding the influence of statins therapy on glycated hemoglobin (HbA1c). This study has valuable strength points; long follow-up period and big sample size.