Source: Diabetes Care  |  Posted 8 years ago

Insulin aspart and lispro appear to produce identical serum insulin levels and are equally effective in correcting carbohydrate and fat metabolism abnormalities in patients with type 1 diabetes, according to the findings of a small observational study.

Both insulin aspart and lispro are rapidly-acting human insulin analogs, which are being increasingly used. However, it is unclear whether they are interchangeable in clinical practice.

To compare the two insulins, Carol Homko, PhD, from the Division of Endocrinology/Diabetes/Metabolism at Temple University School of Medicine, in Philadelphia, Pennsylvania, and colleagues studied the effects of insulin aspart and lispro in 7 C-peptide-negative patients with type 1 diabetes.

Participants' plasma glucose was normalised overnight by intravenous infusion of insulin. The next morning, they received at random subcutaneous injections of either aspart or lispro (mean dose of 9.4 U). The next month the patients returned and received an injection of the other insulin.

Following the injections, the patients' plasma glucose level was clamped at approximately 5.5 mmol/l for the next 4-5 hours with a variable infusion of 20% glucose. The study was ended after 8 hours.

Both insulin analogs produced similar serum insulin levels. Thirty minutes after injection, insulin concentrations increased from an average of 39 to 256 pmol/L for insulin aspart and from 43 to 286 pmol/L for insulin lispro (P=0.24). Insulin levels then declined at similar rates in both groups, reaching basal levels approximately 4 hours after injection.

The two insulins also had similar effects on glucose and fat metabolism. Effects on glucose uptake, glucose oxidation, and endogenous glucose production peaked after about 2 to 3 hours and disappeared after 5 to 6 hours. Effects on lipid metabolism were also similar between the two insulins and peaked at approximately 2 hours and disappeared after about 4 hours.

"To our knowledge, this is the first study comparing action of lispro and aspart on carbohydrate and fat metabolism in the same patients," Dr. Homko and colleagues note.

They conclude that while the study size was small, "our data suggested that these two rapidly acting insulin analogs should be equally effective in treating the metabolic abnormalities of patients with type 1 diabetes."