Dietary patterns and their association with glycated haemoglobin among adults with type 2 diabetes mellitus in urban DR Congo in 2025: a cross-sectional study

Type 2 diabetes mellitus (T2DM) is a growing public health concern in sub-Saharan Africa, where rapid urbanisation and dietary changes contribute to poor glycaemic control among diabetic patients. In the Democratic Republic of the Congo, little is known about how dietary practices affect glycaemic control among diabetic adults. This study assessed dietary patterns and their associations with glycated haemoglobin (HbA1c) among adults with T2DM in Kinshasa, with a focus on socioeconomic factors influencing diet. A cross-sectional survey was conducted in a random sample of 540 adults with T2DM attending 27 primary and 27 secondary health facilities in April 2025. Dietary practices were assessed using an adapted qualitative 7-day food-frequency questionnaire covering 20 food groups. Principal component analysis identified dietary patterns, and survey-clustered generalised linear models were used to examine associations between dietary pattern quintiles and mean HbA1c, adjusting for sociodemographic, lifestyle, and food-insecurity variables. Overall, 442/509 (86.8%) of participants had uncontrolled diabetes (HbA1c ≥ 7%), 40% reported severe household food insecurity, and 60.9% were obese or overweight. Four dietary patterns explained 36.8% of the total variance: 1) vegetable, fish & plant-rich; 2) mixed protein & staple; 3) refined-grain & dairy-sweet; and oil & dairy. Higher adherence to the refined-grain and dairy-sweet pattern was associated with higher HbA1c in Q2 (Adjusted Exp(β) = 1.10; 95% CI: 1.02–1.18), Q3 (Adjusted Exp(β) = 1.09; 95% CI: 1.03–1.15), and Q4 (Adjusted Exp(β) = 1.08; 95% CI: 1.01–1.16), compared with Q1. No clear associations were observed for other dietary patterns. Longer diabetes duration (> 5 years) was associated with higher HbA1c (Adjusted Exp(β) = 1.05; 95% CI: 1.01–1.10), while age was inversely associated (Adjusted Exp(β) = 0.9965; 95% CI: 0.994–0.999). Among clinic-attending adults with T2DM in Kinshasa, a diet high in refined grains and dairy-sweets was associated with poorer glycaemic control. Poor glycaemic control was widespread despite reported dietary adherence, suggesting ineffective nutrition guidance and systemic barriers like food insecurity. The findings argue for the need to integrate culturally adapted nutrition counselling and affordable food-based interventions into diabetes management.