Cost Benefit Analysis of Human and Analog Insulin

Rising insulin costs have created limiting barriers in diabetic therapy plans. A recent study provides data on which insulin types may be the most cost-effective.

The rising costs of medications have become one of the largest barriers to entry towards the path of better health. Patients are not able to adhere to their medication therapy plans if they are unable to afford said medications. Specifically, for patients with diabetes, rising insulin costs have forced some to remain in hyperglycemic states throughout the day, leading to an increased risk of developing secondary vascular complications over time. A recent price analysis by the medication coupon company GoodRx shows that the average price of insulin has increased by over 60% per individual vial in the last five years.

Initiatives towards making insulins more readily available to the public have gained increasing advocacy due to these continuously rising prices. Recently, Colorado has become the first state to cap the out of pocket price of insulin per month supply for insured patients with diabetes. Other initiatives include studies comparing the price and efficacy of available insulins in patients with diabetes to determine the most cost effective options.

A recent retrospective cohort study published in the Journal of the American Medical Association compared the cost savings and efficacy of analog and human insulins in patients with type 2 diabetes that are Medicare beneficiaries. The overall goal of this study was to lay the foundation for newer health initiatives for all patients with diabetes to ensure increased availability of pharmacotherapeutic needs. Patients covered by a specified Medicare advantage plan were enrolled into this study if they filled at least one insulin prescription within a two year enrollment period. Half-way through the enrollment period, the insurer implemented a plan-wide health program to switch patients to a more cost beneficial insulin regimen (i.e. from analog insulins to human insulins), and this was considered the intervention period of the study.

Patients ideal for the insulin transition were those who were on two or more insulin injections or a total dose of greater than 50 units per day, had a history of medication non-adherence, and lacked recurrent hypoglycemic episodes. Insulin doses were switched per a clinician-guided protocol. The primary endpoint observed in this study was the monthly change in average HbA1c as an indicator of overall glycemic control. Secondary endpoints observed included safety outcomes, such as incidence of hypoglycemic and hyperglycemic events, and fiscal outcomes such as total plan spending for each insulin type.

Over 200,000 individual insulin prescriptions were filled by 14,635 plan beneficiaries during the two year enrollment period. Baseline characteristics among the study population were homogenous and did not statistically differ. Baseline mean HbA1c was 8.46% (95% CI: 8.40% – 8.52%) before the switch to human insulins and decreased at a rate of 0.02% (95% CI: 0.01% – 0.03%) per month. At the start of the intervention period, overall HbA1c levels rose significantly by 0.14% (95% CI: 0.05% – 0.23%). After completion of the intervention period, overall HbA1c levels did not significantly change (95% CI: -0.01 – 0.17%; p=0.09) when compared to the 12 month intervention period.

Safety outcomes did not significantly differ between the study periods (i.e. before, during, and after the 12 month intervention period) though absolute differences were biased towards the start of the intervention period, resulting in 14 more serious hypoglycemic events and 26 more serious hyperglycemic events. There were no significant differences in the rate of increase of adverse events between the study periods

The total amount of analog insulin prescriptions filled decreased from 89% to 53% to 30% before, during, and after the intervention period, respectively. The total amount of human insulin prescriptions filled increased from 11% to 47% to 70% before, during, and after the intervention period, respectively. Monthly expenditures for analog insulins decreased by a total of $2,698,562 over the two year study period while monthly expenditures for human insulins increased by a total of $756,593, resulting in an absolute savings difference of $1,941,969, monthly.

Results from this study show a significant, though small, increase in HbA1c and a monthly cost savings of millions after the transition from analog insulins to human insulins in patients with diabetes. The observed increase in overall HbA1c may not be clinically significant as previous studies have demonstrated that such small changes in HbA1c did not result in an increased risk of developing adverse vascular outcomes.

Practice Pearls

• Patients with diabetes treated with analog insulins had a significant minimal increase in HbA1c when transitioned to human insulins.
•  Incidence of serious hypoglycemic or hyperglycemic events were not significantly different between patients treated with analog insulins and human insulins.
• Clinicians should consider the results of this study when treating patients with diabetes requiring insulin who are economically challenged.

Luo J, Khan N, Manetti T, et al. Implementation of a health plan program for switching from analogue to human insulin and glycemic control among medicare beneficiaries with type 2 diabetes. JAMA 2019; 321(4):374-384. DOI: 10.1001/jama.2018.21364

Lee B. GoodRx. How much does insulin cost? Here’s how 22 brands compare. Available at: https://www.goodrx.com/blog/how-much-does-insulin-cost-compare-brands/. Accessed June 3, 2019.

Adam Chalela B.S., PharmD Candidate, USF College of Pharmacy Class of 2020

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