Exploring the association between insulin resistance and moderate to severe acne vulgaris across diverse body mass index categories: A case–control study

Objectives: Acne vulgaris is a highly prevalent chronic inflammatory skin condition that adversely affects patients’ quality of life. Although multiple factors contribute to its development, recent research has increasingly implicated insulin resistance (IR), particularly in individuals with elevated body mass index (BMI). The objective of the study is to examine the relationship between IR, acne severity, and BMI among patients with moderate-to-severe acne vulgaris. Materials and Methods: A hospital-based case–control study was performed at a tertiary care institution in Tamil Nadu, India, from November 2024 to April 2025. The study included 80 participants aged 15–30 years, comprising 40 patients with moderate-to-severe acne vulgaris and 40 age- and sex-matched healthy controls without acne. Acne severity was assessed using the Global Acne Grading System. BMI was categorized using standard criteria. Fasting plasma glucose and serum insulin levels were measured, and IR was calculated using the homeostatic model assessment. Sociodemographic characteristics and lifestyle factors were obtained through structured questionnaires. Statistical analysis involved descriptive measures, independent t -tests, Chi-square tests, and multivariable logistic regression. Results: The mean age of the study population was 21.4 years. IR was observed significantly more frequently in patients with acne than in controls (60% vs. 20%; p <0.05). Among acne patients, the prevalence of IR showed a progressive increase across BMI categories: Normal weight (20%), overweight (50%), and obese (80%). Severe acne was more commonly detected in insulin-resistant individuals compared with those without IR (70% vs. 30%; p <0.01). On multivariate analysis, IR emerged as an independent determinant of acne severity after adjusting for BMI (odds ratio = 3.5; 95% confidence level: 1.6–7.8). Limitations: The single-center cross-sectional design and relatively small sample size limit causal interpretation. Insulin resistance was evaluated using homeostatic model assessment for insulin resistance (HOMA-IR) rather than gold-standard clamp-based methods. Conclusion: IR demonstrates a strong association with greater acne severity, particularly in individuals with higher BMI. Incorporating metabolic evaluation into the assessment of patients with moderate-to-severe acne may support more personalized and effective management strategies.