Introduction and objectives: Studies have associated diabetes with negative impacts on health-related quality of life (HRQoL). Several validated instruments are available to measure HRQoL in people with type 2 diabetes (PwT2D). The objectives of this study were to assess the knowledge of PwT2D followed in primary health care (PHC) about self-care in diabetes and its relationship with quality of life (QoL), and to compare clinical and laboratory parameters with the scores in different domains of the self-care and QoL questionnaires.

Methods: This descriptive-exploratory study was conducted in PHC in the city of Ferraz de Vasconcelos, São Paulo. The study included 199 PwT2D who met the following inclusion criteria: aged over 40 years, with a diabetes diagnosis (least two years), and currently using oral antidiabetic agents and/or insulin. Participants were required to complete two questionnaires: Summary of Diabetes Self-Care Activities Questionnaire (SDSCA) and Diabetes Quality of Life Measure (DQOL-Brazil). Laboratory test results were recovered from participants' medical records.

Results: Clinical and laboratory data of participants, presented as mean and standard deviation, were age 63.1 ± 10.4 years, T2DM duration 10.2 ± 8.8 years, glycated hemoglobin (A_1c) 8.2 ± 2.1%, LDL cholesterol 107.3 ± 36.6 mg/dL, HDL cholesterol 51.3 ± 17.2 mg/dL, triglycerides 175.6 ± 111.6 mg/dL, and estimated glomerular filtration rate 96.7 ± 8.7 mL/min/1.73 m². Total scores for the SDSCA and the DQOL-Brazil were 45.8 ± 16.5 and 93.6 ± 10.5 points, respectively. Cronbach's alpha coefficient, used to assess the internal consistency of the questionnaires, was 0.61 for SDSCA (moderate correlation) and 0.8 for DQoL-Brazil (strong correlation). The Pearson correlation coefficient revealed a weak correlation between the total SDSCA score and T2DM duration (0.172, p = 0.019), with no correlation observed with A_1c levels (-0.042, p = 0.548). A similar pattern was observed for the total DQoL-Brazil score and T2DM duration (0.284, p < 0.0001), and A_1c levels (-0.088, p = 0.213). Correlation analysis for each domain of SDSCA and DQoL-Brazil was also weak for both T2DM duration and A_1c levels. Moreover, correlation analysis between each domain of SDSCA and DQoL-Brazil showed no correlation, even when participants were divided into groups with A_1c < 7.5% and A_1c > 7.5%.

Conclusions: Questionnaires used in this study did not identify a significant impact of self-care diabetes on QoL in PwT2D followed in PHC.