Using a cross-sectional design of 400 primary care patients with diabetes, the authors evaluated demographics, health status, subjective health and mental health, health behaviors, health beliefs, knowledge of diabetes treatment, satisfaction with medical care, and quality of medical care as potential predictors of QoL and QoL in the hypothetical absence of diabetes. Those who reported difficulties meeting basic needs, diabetes-related complications, worse subjective health, and dissatisfaction with medical care were more likely to report worse QoL. Those who reported difficulties meeting basic needs, higher cholesterol level, and worse subjective health also were more likely to report better QoL in the hypothetical absence of diabetes. In addition, diabetes management played a major role in one's QoL in the hypothetical absence of diabetes: Engaging in stricter diabetes self-care and taking pharmaceutical treatment for managing diabetes were associated with better QoL in the hypothetical absence of diabetes. Providing psychosocial support geared toward diabetes self-management may improve patients' QoL. When doing so, social workers need to be aware of the potential trade-off between following medical recommendations that advocate for a strict lifestyle and patients' QoL.