Results:
Forty-three studies met the inclusion criteria, of which 13 studies were used in meta-analysis. The pooled proportion of non-adherence to anti-diabetic medications using the eight-item Morisky Medication Adherence Scale (MMAS) was 43.4% (95% CI: 17.5–69.4; p=0.000) and 29.1% (95% CI: 19.8–38.4; p=0.000) when using the cut-off at 80 or 90%. The pooled proportion of non-adherence was 29.5% (95% CI: 25.5–33.5; p=0.098) when using the four-item Morisky Medication Adherence Scale. The factors for non-adherence based on World Health Organization demonstrated considerable variation of non-adherence to ant-diabetic medication in LMICs depending on the methods used to estimate non-adherence.