Of 41 145 T2DM patients enrolled in the CCMDD, 7 960 (19%) had an available HbA1c result over the study period. A quarter of patients (2 147/7 960; 27%) were optimally controlled at their baseline HbA1c. Of those controlled at baseline, 697 (32%) patients had a repeat test available, with 35% (242/697) changing their status to sub-optimal control.  Patients prescribed dual therapy had a higher rate of sub-optimal glycaemic control (aHR: 1.51; 95% CI:1.17–1.97; p-value: 0.002) compared to those on monotherapy. HbA1c testing frequency in accordance with national guidelines (aHR: 0.43; 95% CI: 0.22–0.85; p-value: 0.014) was associated with lower hazard rates of sub-optimal glycaemic control. 