Purpose: The purpose of this study was to determine if a Health Coaching (HC) approach compared with formal health education (HE) resulted in better health outcomes among type II diabetes (T2DM) patients in improving glycaemic control and oral health, by use of clinical and subjective outcome measures. Methods: The study is part of a prospective intervention among randomly selected T2DM patients (n = 186) in Istanbul, Turkey. The data analysed were clinical [glycated haemoglobin (HbA1C), clinical attachment loss (CAL)] and psychological measures [tooth-brushing self efficacy (TBSES)]. Data were collected initially and at the end of intervention. Participants were allocated randomly to HC (intervention) (n = 77) and HE (control) (n = 111) groups. Results: At baseline, there was no statistical difference between HC and HE regarding clinical and psychological measures, (P > 0.05). At post-intervention the HC group had significantly lower HBA1C and CAL (reduction: 7%, 56%) than the HE group (reduction: HbA1C 0%; CAL 26%), (P ≤ 0.01). Similarly, HC group, compared with HE group, had better TBSES (increase: 61% vs. 25%) and stress (reduction: 16% vs. 1%), (P ≤ 0.01). Among high-risk group patients, the HC patients had significant improvements compared with the HE group (reduction: HbA1C 16% vs. 5%; CAL 63% vs. 18%; stress 39% vs. 2%; fold increase: TBSES 6.6 vs. 3.6) (P ≤ 0.01). Conclusions: The present findings may imply that HC has a significantly greater impact on better management of oral health and glycaemic control than HE. It is notable that the impact was more significant among high-risk group patients, thus HC may be recommended especially for high-risk group patients.