Insulin glargine: a new long-acting insulin product

The pharmacodynamics, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of insulin glargine are reviewed. Current treatment regimens for patients with type 1 diabetes mellitus and some with type 2 are designed to provide a basal insulin level with intermittent preprandial insulin coverage. Insulin glargine precipitates after subcutaneous injection, slowing absorption. Insulin glargine is used as a basal insulin and exhibits a flat pharmacokinetic profile, with a duration of action of at least 24 hours. Hypoglycemia is the most commonly reported adverse effect, especially within the first four weeks after a switch to insulin glargine. Insulin glargine should not be mixed with any other insulin product and should be administered with a syringe that has not been used for other insulin products or other medications. Insulin glargine is administered once daily at bedtime. Patients previously receiving twice-daily isophane insulin (NPH) should receive an insulin glargine dosage 20% less than the total daily dose of NPH insulin. Clinical trials did not consistently show improvements in hemoglobin A1c levels when patients with type 1 diabetes mellitus were switched from NPH insulin once or twice daily to insulin glargine. Insulin glargine should be considered for patients who continue to have elevated morning blood glucose levels and problems with nocturnal hypoglycemia despite receiving NPH insulin at bedtime. In patients with type 2 diabetes mellitus, insulin glargine significantly improved glycemic control compared with once-daily NPH insulin, but not when it was compared with combined treatment with once- or twice-daily NPH insulin. Clinical trials assessing progression of retinopathy and nephropathy and comparing insulin glargine therapy with continuous subcutaneous insulin infusion therapy are needed to more clearly determine insulin glargine's role. Insulin glargine is a new long-acting formulation that can provide prolonged basal glucose control in patients with diabetes mellitus.