Diet Quality, Inflammatory Biomarkers, and Depression Symptoms Among Adults with Type 2 Diabetes in Ogun State

Depression is approximately two to three times more prevalent among people with type 2 diabetes mellitus compared to the general population, and the diet-inflammation-mental health nexus offers a plausible mechanistic pathway warranting investigation in Nigerian clinical populations. This study examines the relationship between diet quality, inflammatory biomarkers, and depression symptoms among adults with type 2 diabetes in Abeokuta, Ogun State, South West Nigeria. An analytical cross-sectional study enrolled 280 confirmed type 2 diabetic patients aged 30 to 70 years attending the diabetes outpatient clinic of Federal Medical Centre Idi-Aba. Diet quality was scored using the Healthy Eating Index adapted for the Nigerian food context, based on a semi-quantitative food frequency questionnaire. Inflammatory biomarkers measured included high-sensitivity C-reactive protein, interleukin-6, and tumour necrosis factor-alpha from fasting blood samples. Depression symptoms were assessed using the Patient Health Questionnaire-9, a validated self-report tool with established psychometric properties in Nigerian populations. Glycated haemoglobin, body mass index, diabetes duration, and comorbidities were recorded as covariates. Structural equation modelling was used to test whether inflammation mediates the association between diet quality and depression symptoms. Findings will contribute to an integrated understanding of dietary, metabolic, and psychological wellbeing in Nigerian diabetic patients and support the development of combined nutrition and mental health support services. Keywords: diet quality, depression, inflammation, type 2 diabetes, Ogun State.