Hypoglycemia among hospitalized patients with diabetes is a common problem. Of the > 8 million patients admitted to US hospitals annually with a diagnosis of diabetes, up to 25% may have a low blood glucose level during hospitalization. As a widely recognized cause of acute, potentially fatal events, hypoglycemia remains a significant barrier to optimal inpatient glycemic control. Although iatrogenic hypoglycemia is associated with adverse outcomes, it may be a marker for illness rather than causal in itself. Several factors, such as administration of exogenous insulin, mismatch of insulin administration with nutrition, and the loss of normal counterregulatory responses, place patients with diabetes at higher risk for hypoglycemia than patients without diabetes. Causes and predictors of hypoglycemia in hospitalized patients with diabetes are discussed. Careful attention to contributing factors, responsiveness to changes in clinical status, and specific institutional protocols and policies can reduce the risk of hypoglycemia. Use of subcutaneous basal-bolus insulin dosing consistent with national guidelines and correction rather than sliding-scale insulin may minimize both hyper- and hypoglycemia. A majority of the literature on inpatient hypoglycemia has been limited to the critical-care setting. This review therefore focuses on hypoglycemia among non-critically ill inpatients with diabetes.