Sitagliptin is a drug used in treatment of type 2 diabetes mellitus. Incretin hormones, including glucagon-like peptide-1 analogue and dipeptidyl peptidase-4 inhibitor have recently been found to regulate glucose metabolism. Thus, the aim of this study was to evaluate the effect of sitagliptin on glycemic control and it is associated side effects in Libyan patients with type 2 diabetes, who had inadequate response to existing anti-diabetic drugs. Hundred patients with a known history of type 2 diabetes were recruited in this study during the period of 2019 and 2020. Sitagliptin (100 mg daily) was added on to the pre-existing therapy for type 2 diabetes and the main outcome measures were a change from the base line in glycated hemoglobin and fasting plasma sugar as well as the incidence of symptomatic hypoglycemia. All patients were engaged from outpatient clinic of National Diabetes and Endocrinology Center at Tripoli, Libya. The findings show that the actions of dipeptidyl peptidase-4 inhibitors improve glycaemic control in the patients, and glycated hemoglobin as well as fasting plasma sugar. Thus, sitagliptin is a profound drug for a comprehensive treatment of patients with type 2 diabetes with a low incidence of hypoglycemia.