Introduction:Sunitinib is an oral inhibitor of tyrosine kinase that was used for the treatment of mRCC. The general side effects are fatigue, asthenia, diarrhea, mucositis, nausea, vomiting, skin changes, hypertension, hypothyroidism and hematologic side effects. In addition, sunitinib-induced hypoglycemia has also been reported. There are limited number of case reports related to sunitinib-induced hypoglycemia. Case presentation:In this case report, we have presented a patient with type 2 diabetes mellitus (DM) with emerging severe hypoglycemia after sunitinib treatment. It was shown that blood glucose levels were normalized two weeks after the interruption of sunitinib. Conclusion:Although the underlying mechanism of sunitinib-induced hypoglycemia is not completely understood, sunitinib can be regarded to have an antidiabetic effect. In the literature, there are some reports about sunitinib/other TKI induced hypoglycemia; however, life threatening hypoglycemia is rare. There is no case report of severe hypoglycemia due to imatinib; however, there are two case reports with severe hypoglycemia due to sunitinib treatment. Symptomatic hypoglycemic episodes due to sunitinib may lead to hospital admission. Diabetic patients may develop severe hypoglycaemia and it should be kept in mind that the discontinuation of antihyperglycemic treatment may be required. Therefore, blood glucose levels should be closely monitored in diabetic patients with mRCC during sunitinib therapy.