After implementing a new formulary to encourage use of lower-cost human insulin, the average A1C among Medicare Advantage enrollees increased by 0.14%. For reference, a “clinically meaningful” change in A1C is considered to be 0.5% or more.

The retrospective study looked at almost 15,000 adults over the age of 65 with type 2 diabetes. Once individuals switched to human insulin (premixed 70/30 or NPH), A1C increased by an average of 0.14% from a base of 8.46%. In the follow-up period of one year, average A1C did not increase significantly.

Additionally, there were no significant changes in rates of serious hypoglycemia or serious hyperglycemia following the change. Frequently, hypoglycemia and weight gain are considerations with human insulin. This study did not include people with a history of recurrent hypoglycemia, however, so the results do not apply to individuals with that concern.

NPH, regular, and 70/30 insulin (a mix of the two) have periods where they lower blood sugar more than at other times, called a “peaking effect.” However, these insulins tend to be less expensive than more stable analogue insulins. They are available at Walmart for $25, and in some states, are even available over the counter. For individuals for whom the cost of medication is a significant factor in deciding treatment, the savings associated with switching from analogue insulins may outweigh the challenges. People considering this should discuss the risks and benefits candidly with their doctor before making any changes.