Combination therapy with insulin and oral agents: optimizing glycemic control in patients with type 2 diabetes mellitus.

The United Kingdom Prospective Diabetes Study (UKPDS) showed that tight glycemic control with any of several therapeutic regimens has the potential to significantly reduce the risk for long-term microvascular complications of type 2 diabetes. An important question that remains to be answered is what is the best approach to optimizing glycemic control in patients with this disease. This article reviews results of studies in which insulin was used alone or in combination with oral antidiabetic agents for treatment of patients with type 2 diabetes. Analysis of comparative studies (13 in insulin-naive and 26 in previously insulin-treated patients) showed that combination therapy involving one to two insulin injections per day plus oral therapy is usually more effective than insulin monotherapy for achieving and maintaining glycemic control. Combination treatment for type 2 diabetes can be significantly improved by newly developed preparations that lack the major limitations of older products. Once-daily administration of isophane insulin (NPH insulin) is limited by a 15-18-h duration of action and a peak effect that occurs about 6 h after injection. Insulin glargine, a new insulin analogue developed using recombinant DNA technology, has a flat pharmacodynamic profile and a 24-h duration of action. Results from a recent comparative study indicate that insulin glargine plus oral therapy may provide better post-dinner glucose control as well as less symptomatic and nocturnal hypoglycemia than oral therapy combined with NPH insulin. The studies reviewed in the present article support the conclusion that combination therapy with insulin glargine combined with one or more oral antidiabetic agents may be the treatment of choice for achieving glycemic control in patients with type 2 diabetes. Copyright 2002 John Wiley & Sons, Ltd.