Background: Type 2 diabetes mellitus (T2DM) is not only a disorder of glucose regulation but also a disease driven by chronic low-grade inflammation. India, particularly South India, bears a disproportionately high burden, with patients often presenting at a younger age and with more severe complications. While glycated hemoglobin (HbA1c) is the established gold standard for assessing long-term glycemic control, inflammatory markers such as C-reactive protein (CRP) have gained attention for their role in insulin resistance and vascular damage. Elevated CRP may reflect ongoing metabolic stress and predict poor outcomes even in patients with apparently controlled blood sugars. Aim: This study aimed to evaluate the relationship between CRP and HbA1c in South Indian patients with type 2 diabetes mellitus and to determine whether inflammation parallels poor glycemic control. Methods: A cross-sectional study was conducted at Dr. B. R. Ambedkar Medical College and Hospital, Bangalore, from January 2025 to July 2025. A total of 100 patients aged 30-70 years with confirmed T2DM were enrolled. Patients with acute infections, autoimmune conditions, chronic kidney disease, liver disease, or recent cardiovascular events were excluded. Clinical histories, anthropometric measurements, and comorbidities were documented. HbA1c was measured using high-performance liquid chromatography (HPLC), and CRP levels were assessed using a high-sensitivity immunoturbidimetric method. Statistical analyses were performed using SPSS v25. Results: Of the 100 patients studied, 58 were male and 42 female, with a mean age of 53.2 ± 8.7 years and mean diabetes duration of 7.1 ± 3.9 years. The mean HbA1c was 8.2 ± 1.5%, while the mean CRP was 4.4 ± 2.1 mg/L. Patients with HbA1c <7% had mean CRP levels of 2.7 mg/L, those with HbA1c between 7-8% had 4.0 mg/L, and patients with HbA1c >8% had significantly higher CRP levels averaging 6.0 mg/L. Correlation analysis revealed a strong positive association between CRP and HbA1c (r = 0.61, p < 0.001). This relationship remained significant even after adjusting for BMI, hypertension, and duration of diabetes (adjusted β = 0.47, p < 0.001). Subgroup analysis showed that obese and hypertensive patients had consistently higher CRP levels compared to their non-obese, normotensive counterparts. Conclusion: This study highlights a significant positive correlation between CRP and HbA1c in South Indian patients with T2DM. Elevated CRP levels were consistently associated with poor glycemic control, obesity, and longer disease duration, underscoring the role of inflammation in the pathophysiology of diabetes. CRP may serve as a useful adjunct biomarker alongside HbA1c, allowing better risk stratification and early identification of patients at higher risk for complications. Incorporating inflammatory markers into diabetes management protocols may help in tailoring more holistic therapeutic strategies.

Type 2 diabetes mellitus, C-reactive protein, HbA1c, inflammation, insulin resistance, South India, obesity, hypertension, metabolic stress, glycemic control, biomarkers, Vascular damage