Introduction In low- to middle-income countries such as Vietnam, urgent measures are required to prevent and control type 2 diabetes and its complications. This study measured the effect of a 3-month patient education and self-management intervention in a low-resource setting on diabetes knowledge and levels of blood glucose control. Methods This was a single-center randomized controlled study among adult outpatients with type 2 diabetes. Patients were randomly assigned to 3-month community intervention consisting of group education for type 2 diabetes knowledge, diet, exercise in combination with usual diabetes care, or to usual diabetes care alone (control). Diabetes knowledge was measured with a modified Michigan University Diabetes Knowledge Test (MDKT). Other study outcomes included change in mean HbA1c, fasting blood glucose (FBG), and systolic blood pressure (SBP). Results A total of 364 patients were randomized, 182 to the intervention group and 182 to control. The two groups were similar regarding main baseline characteristics. The male/female ratio was 45.1%/54.9% and mean age was 62.2 ± 9.3 years. Approximately half the patients (48.1%) were overweight and 15.7% were obese, mean baseline HbA1c was 8.21 ± 1.92%, and only 29.9% of participants had a baseline HbA1c < 7.0%. At baseline, diabetes knowledge was “very poor” or “poor” in 63.7% of patients. After a 3-month follow-up, the proportion achieving the target MDKT score increased from 37.4% to 81.3% in the intervention group and from 35.2% to 51.7% in the control (between-group difference P < 0.001). The estimate (SD) of the difference between intervention and control groups was − 1.63 (2.16), 95% CI − 2.07 to − 1.18. Mean changes from baseline HbA1c were − 0.54 ± 1.41% and − 0.18 ± 1.33% in the intervention and control groups, respectively ( P = 0.012). Among those with poor glycemic control (HbA1c ≥ 7%) at baseline, mean changes at 3 months were − 0.80 ± 1.52% vs 0.41 ± 1.47%, respectively, ( P = 0.013). Statistically significant decreases in FBG and SBP were also observed in the intervention group at 3 months, but not in the control group. Multivariate analysis revealed the variables with the strongest influence on blood glucose control at 3 months were study group, baseline MDKT score, diabetes duration, and baseline HbA1c (all P ≤ 0.05). Conclusion Provision of a structured educational program to Vietnamese people living with type 2 diabetes is effective at improving disease knowledge and is associated with better glycemic control. Larger and longer-term studies are now warranted to confirm these findings. Trial Registration This trial was retrospectively registered on 27 May 2020 through the https://clinicaltrials.gov site with the following identifier: NCT04403841 Su...