Narrative review: a rational approach to starting insulin therapy.

Background: The emergence of multiple insulin products has provided new opportunities to achieve diabetes control. However, the number of options has raised concerns about the optimal choices of products.

Purpose: To briefly review the pharmacologic characteristics of currently available insulin products and to suggest an initial insulin regimen based on common blood glucose profiles among patients with diabetes.

Data Sources: Relevant manuscripts were identified through a MEDLINE search (1996 to 25 February 2006) of the English-language literature. The key phrase used was therapeutic use of insulin. The literature search was limited to core clinical journals that have accessible full texts.

Study Selection: Clinical trials and authoritative reviews published between 1996 and February 2006 were selected. A total of 420 manuscripts was reviewed.

Data Extraction: The authors independently reviewed the relevant available literature. This literature, along with the authors' clinical experience, was used to construct practical suggestions.

Data Synthesis: Several new insulin and insulin analogue preparations are now available for clinical use. Used as prandial insulin (for example, insulin lispro, insulin aspart, or insulin glulisine) and basal insulin (for example, insulin glargine or insulin detemir), the analogues simulate physiologic insulin profiles more closely than the older conventional insulins. There is currently no strong rationale favoring glargine, neutral protamine Hagedorn insulin, insulin detemir, or fixed-ratio insulin preparations as the preferred agent for initiating insulin therapy.

Limitations: This was a retrospective review of previously published manuscripts chosen at the authors' discretion.

Conclusions: The advent of recombinant DNA technology made it possible to overcome limitations in the time-action profiles of conventional insulins. Insulin therapy must be individualized. Nevertheless, certain subgroups of patients with diabetes can be differentiated from each other according to the pattern of blood glucose changes during the day. On the basis of the blood glucose profile, the authors suggest an initial insulin regimen that can be used to evaluate individual responsiveness and plan a long-term regimen.