On average, people with type 1 diabetes who injected an insulin analog had slightly lower—one-tenth of 1 percent —blood sugar levels than those who used regular insulin, according to the review of 49 studies.

For type 2 diabetes patients, there was no real difference in blood sugar levels between those who used analog or regular insulin. There were also a similar number of low blood sugar episodes in both sets of patients, regardless of the type of insulin used, said Dr. Andrea Siebenhofer of the Medical University of Graz and colleagues.

“Our analysis suggests only a minor benefit of short acting insulin analogs in the majority of diabetic patients treated with insulin,” Siebenhofer said.

None of the studies in the review examined the possible long-term effects of insulin analogs, including how they may affect the health of people with diabetes-related complications such as heart disease and kidney failure. Until these effects are studied, there should be “a cautious response to the vigorous promotion of insulin analogs,” Siebenhofer warned.

The Cochrane reviewers, several of whom have studied short and long-acting insulin analogs on behalf of pharmaceutical companies that sell the drugs, analyzed 49 studies involving 8,274 diabetes patients. Most of the participants were being treated for type 1 diabetes, and three-quarters of the studies used the analog Humalog.

Family physician Dr. Michael Schooff of Clarkson Family Medicine in Omaha states that, “Most endocrinologists I know believe in the ‘if it ain’t broke, don’t fix it’ philosophy, so if a patient is doing well on any insulin regimen, they are unlikely to change. On the other hand, I haven’t seen an endocrinologist start a newly diagnosed patient -- or new to start on insulin --on a conventional insulin regimen. All of the new prescriptions I see are for very-rapid or long-acting analogs,” Schooff said. “Where the analogs have an advantage is in allowing the insulin regimen and delivery to fit easier into people’s life and lifestyle,” he said.
A. Siebenhofer et al. Short acting insulin analogues versus regular human insulin in patients with diabetes mellitus. The Cochrane Database of Systematic Reviews 2006, Issue 2.

The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.