Diabetes mellitus is a common metabolic disorder characterized by high blood glucose levels resulting from an insulin deficiency (type 1 diabetes mellitus) or a combination of insulin deficiency and insulin resistance (type 2 diabetes mellitus). The chronic hyperglycemia associated with diabetes mellitus can cause damage to the eyes, kidneys, heart and peripheral circulation, resulting in substantial morbidity, premature mortality and considerable healthcare costs.In both type 1 and type 2 diabetes mellitus, quality of glycemic control has been shown to be a major factor in the prevention of microvascular complications, and tight blood glucose control is the primary goal for all patients with diabetes mellitus.In patients with type 1 diabetes mellitus, multiple daily injections of exogenous insulin and frequent monitoring of blood glucose levels are required to achieve tight glycemic control. Patients with type 2 diabetes mellitus may achieve initial glycemic control with diet and lifestyle interventions alone; however, a large percentage of patients will require pharmacological therapy, first with an oral antidiabetic agent and, ultimately, with insulin.Premixed insulin formulations, consisting of fixed ratios of short- and intermediate-acting insulins, are a convenient and effective treatment option which account for ≈40% of insulin use worldwide. Until recently, the only premixed formulations available contained varying proportions of human regular insulin and human isophane insulin suspension (NPH). However, new premixed formulations containing insulin lispro (a rapid-acting insulin analog) and insulin lispro neutral protamine suspension (NPL) [an intermediate-acting insulin analog] are now available.Insulin lispro mix75/25 (Humalog®Mix75/25™) is a premixed formulation containing 25% insulin lispro and 75% NPL which has been investigated for use in patients with type 1 and with type 2 diabetes mellitus. Administered twice daily immediately before breakfast and dinner, insulin lispro mix75/25 provides better control of postprandial blood glucose, provides similar overall glycemic control, appears to be preferred by patients and may reduce nocturnal hypoglycemia compared with a similar premixed formulation containing 30% human regular insulin and 70% NPH (human insulin 70/30; Humulin® 70/30, Novolin®70/30). Insulin lispro mix75/25 has a rapid onset of action, allowing for administration immediately before a meal, whereas patients need to administer human insulin 70/30 30 to 60 minutes prior to meals. Insulin lispro mix75/25 also improves glycemic control in patients whose type 2 diabetes mellitus is not well controlled by oral agents.ConclusionInsulin lispro mix75/25 is suitable for patients wishing to use premixed insulin formulations and may offer several benefits over human insulin 70/30.