Relative to participants in the control group , CHWs had a positive impact on net HbA1c improvements at 3 months ( -0.42 % [ -4.62 mmol/mol ] ) , 6 months ( -0.47 % [ -5.10 mmol/mol ] ) , 12 months ( -0.57 % [ -6.18 mmol/mol ] ) , and 18 months ( -0.55 % [ -6.01 mmol/mol ] ) .