To evaluate the impact of telehealth use during the COVID-19 pandemic on glycaemic control and other clinical outcomes among patients with type 2 diabetes. We used electronic health records from the Research Action for Health Network (REACHnet) database for patients with type 2 diabetes who had telehealth visits and those who only received in-person care during the pandemic. A quasi-experimental method of difference-in-difference with propensity-score weighting was implemented to mitigate selection bias and to control for observed factors related to telehealth use. Outcomes included glycated haemoglobin (HbA1c) and other clinical measures (low-density lipoprotein [LDL] cholesterol, blood pressure [BP], and body mass index [BMI]). Patients using telehealth had better HbA1c control compared to those receiving in-person care only during the pandemic. The telehealth group saw a significant average decrease of 0.146% (95% confidence interval [CI] -0.178% to -0.1145%; P < 0.001) in HbA1c levels over time. The proportion of patients with average HbA1c levels >7% decreased by 0.023 (95% CI -0.034, -0.011; P < 0.001) in the treatment group relative to the comparison group. Modest benefits in the control of LDL cholesterol levels, diastolic BP, and BMI were found in association with telehealth use. Our findings suggest that telehealth services contributed to better glycaemic control and management of other clinical outcomes in patients with type 2 diabetes during the pandemic. Factors unmeasured in this study would need to be further explored to better understand the impact of telehealth.