Abstract: Electroconvulsive therapy (ECT) is often performed for patients with psychiatric disorders who also have diabetes mellitus. Some research has suggested that the course of ECT treatments does not have a consistent effect on blood glucose, but little data exist to inform the clinician about the effects of individual ECT treatments on blood glucose. In this study, 18 patients with type 2 diabetes mellitus were treated with ECT for severe depressive illness. For each patient, a fingerstick blood glucose was routinely obtained before and approximately 20 minutes after each ECT treatment. We found a mean rise of blood glucose after each treatment of approximately 9%, similar to the mean rise of blood glucose among nondiabetic patients undergoing ECT found in a previous study. There were no cases of clinically significant rise or fall in blood glucose. We provide recommendations for management of diabetics during ECT.