Implementation of a Health Plan Program for Switching From Analogue to Human Insulin and Glycemic Control Among Medicare Beneficiaries With Type 2 Diabetes
Authors: Jing Luo, Nazleen F. Khan, Thomas Manetti, Jim Rose, Ani Kaloghlian, Balu Gadhe, Sachin H. Jain, Joshua J. Gagne, Aaron S. Kesselheim
Journal: JAMA (2019)

<h3>Importance</h3> Prices for newer analogue insulin products have increased. Lower-cost human insulin may be effective for many patients with type 2 diabetes. <h3>Objective</h3> To evaluate the association between implementation of a health plan–based intervention of switching patients from analogue to human insulin and glycemic control. <h3>Design, Setting, and Participants</h3> A retrospective cohort study using population-level interrupted times series analysis of members participating in a Medicare Advantage and prescription drug plan operating in 4 US states. Participants were prescribed insulin between January 1, 2014, and December 31, 2016 (median follow-up, 729 days). The intervention began in February 2015 and was expanded to the entire health plan system by June 2015. <h3>Exposures</h3> Implementation of a health plan program to switch patients from analogue to human insulin. <h3>Main Outcomes and Measures</h3> The primary outcome was the change in mean hemoglobin A<sub>1c</sub>(HbA<sub>1c</sub>) levels estimated over three 12-month periods: preintervention (baseline) in 2014, intervention in 2015, and postintervention in 2016. Secondary outcomes included rates of serious hypoglycemia or hyperglycemia using<i>ICD-9-CM</i>and<i>ICD-10-CM</i>diagnostic codes. <h3>Results</h3> Over 3 years, 14 635 members (mean [SD] age: 72.5 [9.8] years; 51% women; 93% with type 2 diabetes) filled 221 866 insulin prescriptions. The mean HbA<sub>1c</sub>was 8.46% (95% CI, 8.40%-8.52%) at baseline and decreased at a rate of −0.02% (95% CI, −0.03% to −0.01%;<i>P</i> &lt;.001) per month before the intervention. There was an association between the start of the intervention and an overall HbA<sub>1c</sub>level increase of 0.14% (95% CI, 0.05%-0.23%;<i>P</i> = .003) and slope change of 0.02% (95% CI, 0.01%-0.03%;<i>P</i> &lt; .001). After the completion of the intervention, there were no significant differences in changes in the level (0.08% [95% CI, −0.01% to 0.17%]) or slope (&lt;0.001% [95% CI, −0.008% to 0.010%]) of mean HbA<sub>1c</sub>compared with the intervention period (<i>P</i> = .09 and<i>P</i> = 0.81, respectively). For serious hypoglycemic events, there was no significant association between the start of the intervention and a level (2.66/1000 person-years [95% CI, −3.82 to 9.13];<i>P</i> = .41) or slope change (−0.66/1000 person-years [95% CI, −1.59 to 0.27];<i>P</i> = .16). The level (1.64/1000 person-years [95% CI, −4.83 to 8.11];<i>P</i> = .61) and slope (−0.23/1000 person-years [95% CI, −1.17 to 0.70];<i>P</i> = .61) changes in the postintervention period were not significantly different compared with the intervention period. The baseline rate of serious hyperglycemia was 22.33 per 1000 person-years (95% CI, 12.70-31.97). For the rate of serious hyperglycemic events, there was no significant association between the start of the intervention and a level (4.23/1000 person-years [95% CI, −8.62 to 17.08];<i>P</i> = .51) or slope (−0.51/1000 person-years [95% CI, −2.37 to 1.34];<i>P</i> = .58) change. <h3>Conclusions and Relevance</h3> Among Medicare beneficiaries with type 2 diabetes, implementation of a health plan program that involved switching patients from analogue to human insulin was associated with a small increase in population-level HbA<sub>1c</sub>.