Objective: To evaluate the clinical and economic effects of a managed care organization’s conversion program switching Medicare beneficiaries with type 2 diabetes mellitus from analog to human insulin.

Methods: A consecutive sample of 14,635 participants who filled insulin prescriptions between January 2014 and December 2016 were identified from a Medicare Advantage and prescription drug plan operating in 4 U.S. states (CA, AZ, NV, VA). Outcomes were mean hemoglobin A1c (%), rates of severe hypoglycemia or hyperglycemia events and risk of reaching the Part D coverage gap. Data were analyzed using interrupted time series and segmented regression with cut points at the beginning and end of 2015.

Results: 14,635 members (mean age=72.5) filled 221,866 insulin prescriptions. Insulin conversion decreased the proportion of scripts filled by analog insulins from 90% to 30%. The baseline mean hemoglobin A1c was 8.46% and decreased at a rate of -0.02% per month during 2014. The beginning of the conversion program in 2015 was associated with a level change of +0.14% (p<0.01) and a slope change of 0.02% (p<0.01). The baseline rate of severe hypoglycemia was 4.21 per 1000-person years (py) and increased at a rate of 0.36/1000py during 2014. The baseline rate of severe hyperglycemia was 22.33/1000py and increased at a rate of 0.30/1000py. For both hypoglycemia and hyperglycemia, the level and slope changes in the 12-month intervention and post-intervention segments were not statistically significant. The intervention reduced the risk of reaching the coverage gap by 55% (HR 0.45, nominal 95% CI: 0.43-0.48, p<0.001).

Conclusions: Switching Medicare beneficiaries with diabetes from analog to human insulin did not change the rates of hospitalization for hypoglycemia or hyperglycemia, slightly increased mean A1c, and reduced the risk of reaching the Part D coverage gap.


J. Luo: Consultant; Self; Alosa Health, Inc.. N.F. Khan: None. T. Manetti: None. J.J. Rose: None. A. Kaloghlian: None. B. Gadhe: None. S.H. Jain: Employee; Self; CareMore Health. J. Gagne: Research Support; Self; Eli Lilly and Company, Novartis Pharmaceuticals Corporation. A. Kesselheim: None.

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