Effect of medication adherence on clinical outcomes in type 2 diabetes: analysis of the SIMPLE study

OBJECTIVE: Medication adherence is impacted by regimen complexity. The SIMPLE (Simple basal Insulin titration, Metformin Plus Liraglutide for type 2 diabetes with very Elevated HbA1c) study compared GLP1RA plus basal insulin (GLP1RA+BI) to basal-bolus insulin (BBI) regimen in participants with very uncontrolled type 2 diabetes mellitus (T2DM). This analysis aimed to evaluate medication adherence to GLP1RA+BI compared with BBI, the effect of adherence on clinical and patient-reported outcomes, and baseline predictors of adherence. RESEARCH DESIGN AND METHODS: This was an analysis of the SIMPLE study based on prespecified outcome. The study took place in pragmatic, real-world setting. A total of 120 adults with T2DM and HgbA1c≥10% were randomized to detemir plus liraglutide, or detemir plus aspart before each meal; 6-month follow-up. The main outcomes evaluated were: adherence, HgbA1c, weight, quality of life, and hypoglycemia. Adherence rate was calculated for each study medication at each follow-up visit; participants were classified as ≥80% or <80% adherent. RESULT: A higher percentage of participants in the GLP1RA+BI compared with the BBI group had ≥80% adherence to detemir (59.3% vs 35.7%, p=0.02) as well as liraglutide versus aspart (57.4% vs 30.4%, p=0.007). Higher age was predictive of ≥80% adherence (OR per 5-year increment=1.48, 95% CI 1.09 to 2.0, p=0.01). Higher adherence led to greater improvement in HbA1c and weight in both groups. Treatment with GLP1RA+BI compared with BBI led to greater improvement in HbA1c, weight, and quality of life and lower risk of hypoglycemia even after adjusting for the difference in adherence between groups. CONCLUSIONS: Adherence was higher with the simplified regimen of GLP1RA+BI compared with BBI. Greater adherence to the simpler regimen amplified the treatment effect on HbA1c, weight, quality of life, and risk of hypoglycemia, yet statistically significant greater benefits were noted even when adjusted for adherence. TRIAL REGISTRATION NUMBER: NCT01966978