Comparison of insulin glargine and NPH insulin in the treatment of type 2 diabetes: a review of clinical studies.

Despite the evidence-based approach to management of Type 2 diabetes outlined in current diabetes practice guidelines, a large proportion of patients are achieving suboptimal glycemic control. A substantial amount of data exists comparing insulin glargine and neutral protamine Hagedorn (NPH) insulin for long-acting basal insulin coverage. The objective of this systematic review was to provide a balanced appraisal of existing clinical evidence and to determine the appropriate step in therapy for insulin glargine or NPH insulin. Relevant English language articles from 1996 to 2005 were identified through searches of the National Center for Biotechnology Information PubMed database. Search terms included neutral protamine Hagedorn, NPH, insulin glargine, insulin therapy, Type 2 diabetes, insulin analogs, HOE901, and HOE-901. Studies were compared regarding designs, primary and secondary efficacy parameters, glycosylated hemoglobin A1c (A1C), fasting plasma glucose (FPG), incidence of hypoglycemia, and other safety assessments. Six original multicenter, randomized, open-label, parallel-group trials conducted in Europe or the United States, ranging in duration from 4 to 52 weeks, met the inclusion criteria. Two additional analyses represented a subanalysis and a study extension. All of the studies compared insulin glargine with NPH insulin given once or twice daily as monotherapy or in conjunction with oral antidiabetic agents in patients with Type 2 diabetes. Based on available evidence, insulin glargine has shown equal clinical efficacy to that of NPH insulin and similar reductions in A1C and is associated with similar or lower FPG levels. Recent studies also have demonstrated that less frequent nocturnal hypoglycemia incidence is associated with insulin glargine compared with NPH insulin. The known pathophysiology of Type 2 diabetes and the need for basal insulin treatment are presented as rationale for comparison of these insulins.