Knowledge is important to control blood sugar and prevent complications and subsequently have an impact on the quality of life (QOL) of type 2 diabetes mellitus (T2DM) patients as a response to their health. This study aimed to determine the correlation between level of knowledge and QOL in type 2 DM (T2DM) patients, also its related factors. This cross-sectional study was conducted in a Public Hospitals, Buleleng, Bali on September 2020. Inclusion criteria included T2DM outpatients who ≥aged 18 years, get similar therapy for at least 3 months, filling out the questionnaire completely, able to communicate well, and not in a pregnant/breastfeeding condition. Data were obtained by medical records, questionnaires DKQ-24 (knowledge) and EQ-5D-5L (QOL). Correlation between knowledge and QOL of T2DM patients and its related factors were analyzed using bivariate statistical tests. Finding of 150 respondents demonstrated mostly were ≥60 years old (53.3%), female (50.7%), first educational level (64%), not working (54%), low income (49.3%), >5 years of T2DM duration (44%), no complications (75.3%), taking 4-6 item medicines (66.7%), moderate knowledge level (70.7%) with QOL based on the utility score was 0.892±0.154 and VAS was 59.73±20.07. Statistical tests showed there was a significant correlation between knowledge and QOL based on utility value (p=0.01), but not with VAS value (p=0.165). These was reinforced by age has a significant correlation with knowledge (p=0.042), also employment status and complications condition has a significant correlation with QOL (p<0.05). Patients with a higher level of knowledge have a better QOL, despite different backgrounds.