Diabetes mellitus among nurses warrants urgent attention due to the significant health risks associated with the condition, which may adversely affect their quality of life and professional functioning within healthcare settings. This study adopted a correlational research design and targeted a population of 106 nurses diagnosed with diabetes mellitus at the University of Port Harcourt Teaching Hospital and the Rivers State University Teaching Hospital. A census sampling technique was employed, whereby all 106 diabetic nurses were included in the study. Data were collected using a structured questionnaire, which demonstrated a reliability coefficient of 0.81. The collected data were analyzed using the Statistical Package for the Social Sciences (SPSS) version 27, with regression analysis applied at a 0.05 level of significance. The result indicated that the highest predictor of quality of life among diabetic nurses was duration of illness and quality of life (r = 0.82, p<0.05), and 68.1% of quality of life of diabetic nurses was predicted by the duration of illness (R² = 0.681). There was a high prediction between presence of complication and quality of life (r = 0.89, p<0.05), and 89.0% of quality of life of diabetic nurses was predicted by the presence of complication (R² = 0.890). The result indicated that there was a high prediction between blood sugar control and quality of life (r = 0.87, p<0.05), and 79.5% of quality of life of diabetic nurses was predicted by the blood sugar control (R² = 0.795). It was concluded that the predictors of quality of life among nurses with diabetes mellitus in public tertiary health institutions in Rivers State were basically disease-specific factors such as presence of complications, blood sugar control, and duration of illness. It was recommended among others that, nurses with diabetes mellitus should prioritize self-care and engage in regular self-care activities such as maintaining a healthy weight, regularly track blood glucose level, and stay connected by regularly communicating with healthcare providers and support group to improve overall quality of life.