Clinical effectiveness of a chronic disease management program on glycemic control in type 2 diabetes mellitus: a difference-in-differences analysis in Indonesian primary care

Background: Indonesia's chronic disease management initiative, Prolanis, was instituted to reinforce primary healthcare for type 2 diabetes mellitus (T2DM). This study sought to ascertain the effectiveness of Prolanis in improving glycemic control among individuals with T2DM. 

Methods: This retrospective cohort study was conducted across multiple healthcare facilities in Semarang, Indonesia. The study included T2DM patients aged ≥18 years who were newly enrolled in Prolanis from January 2021 to December 2024. HbA1c and fasting plasma glucose (FPG) were assessed at baseline and after 12 months of follow-up. Multivariable difference-in-differences (DiD) and subgroup analyses were performed using generalized estimating equations. The inverse probability of treatment weighting was employed to balance baseline differences. 

Results: The analytical sample comprised 491 participants. After covariate adjustment, the probability of achieving well-controlled HbA1c increased by 9.7% in the Prolanis group, while it declined by 13.9% in the control group, yielding a DiD estimate of 22.6% (p < 0.001). Prolanis participants had higher odds of achieving HbA1c <7% over time than the control group (adjusted OR 3.63, 95% CI: 1.87–7.04). In contrast, no statistically significant difference was observed for FPG control. Subgroup analyses suggested stronger associations with HbA1c control among participants aged ≥60 years and non-insulin users. The weighted model yielded findings that were directionally consistent with the primary analysis. 

Conclusion: Prolanis participation was associated with improved HbA1c control, but not with improved FPG control. These findings emphasize the potential contribution of structured primary care interventions to improving diabetes outcomes, particularly among older adults and non-insulin users.