Sociodemographic and Lifestyle Correlates of Glycemic Control in Patients with Diabetes: A Monocentric Pilot Study

Background/Objectives: Despite extensive evidence on the global burden of diabetes mellitus (DM), there is a lack of research on how sociodemographic and lifestyle factors collectively impact glycemic control and diabetes-related complications. This pilot study aimed to identify correlates of glycemic regulation, with a focus on physical activity (PA), education, and clinical variables, among adults with DM in Croatia. Methods: A cross-sectional study was conducted at the national reference center for diabetes, including 95 adult patients with type 1 or type 2 DM. Data were collected via a structured questionnaire and clinical records, covering sociodemographic characteristics, physical activity patterns, and laboratory indicators. Statistical analyses included descriptive statistics, t-tests, chi-square tests, correlation and regression analyses, and K-means clustering. Results: The mean HbA1c was 6.9% (SD = 1.3), with 33.7% of participants exceeding the 7.5% threshold. Higher education (β = −0.48, p = 0.013) and engagement in strength and balance training (β = −0.32, p = 0.041) were independently associated with lower HbA1c levels. Diabetes duration (β = 0.03, p = 0.004) and type 2 diabetes (β = 0.38, p = 0.030) were positive predictors of HbA1c. PA frequency and intensity were not significantly associated with glycemic control (p = 0.479). Cluster analysis identified three distinct profiles, with Cluster 2 (N = 10) exhibiting poor control (mean HbA1c = 9.8%) despite engaging in moderate activity. HbA1c > 7.5% was significantly associated with hypertension (OR = 3.70, 95% CI: 1.34–10.21) and retinopathy (OR = 2.82, 95% CI: 1.14–6.98). Age was the only significant predictor of cardiovascular comorbidities (OR = 1.12, p = 0.019). Education level was a predictor of participation in strength and balance training (OR = 2.45, p = 0.025). Conclusions: Glycemic control in individuals with diabetes is influenced by a combination of behavioral, clinical, and educational factors. Strength and balance training, as well as higher education, were associated with lower HbA1c levels, while older age and type 2 diabetes were indicators of a greater risk. Tailored interventions promoting structured PA and targeting educational disparities may improve clinical outcomes in this population.