OBJECTIVES

: Despite the arsenal of available treatment options, a large proportion of patients with type 2 diabetes (T2D) have inadequate glycemic control. Poor medication adherence has been associated with a lack of improvement in achieving glycemic targets, limiting the full effectiveness of therapy and resulting in potentially avoidable morbidity and mortality. The objective of our study was to measure the impact of poor medication adherence on HbA1c and weight levels in T2D patients.

METHODS

: A systematic literature review was conducted that included publications if they reported percent change in HbA1c or weight change per quantitative measure of adherence (e.g., Proportion of Days Covered). The change in HbA1c reported in each study for 100% adherent patients or per every 25% and 10% reduction in adherence level was either estimated directly from the available results, or assumed to be linear and figures extrapolated accordingly. Changes in weight in kg per 10% reduction in adherence were taken from the studies.

RESULTS

: Fourteen studies were identified on the impact of adherence on HbA1c change. The weighted average of all findings was used to account for sample size differences. For every 25% and 10% decrement in adherence, the impact on HbA1c was reduced by 0.20% and 0.08%, respectively. Only 1 study was identified on weight changes and adherence level to diabetes-related medications. For every 10% reduction in the adherence the change in weight with GLP-1 RA, DPP-4 and SU is attenuated by at least -0.64, 0.16 and 0.02 Kg respectively.

CONCLUSIONS

: Poor adherence leads to a lower reduction of HbA1c level than the one reported in clinical trials, but also to a reduced weight loss or weight gain depending on the antidiabetes treatment evaluated.