Background: Leprosy is an infection by Mycobacterium leprae, which influenced by cellular immunity. Leprosy tends to occur in low socio-economic and nutrition groups. Researchers try to prove the role of nutrition in the pathogenesis of leprosy. Insulin-like growth factor-1 (IGF-1) as a marker of nutritional status shown to play a role in cellular immunity. Objective: To evaluate the correlation between IGF-1 with bacterial index (BI) on leprosy patients in Bali. Methods: Cross-sectional study in Sanglah Public General Hospital, Denpasar of patients with paucibacillary (PB) and multibacillary (MB) leprosy were assessed for BI using slit-skin smear. All patients were tested for plasma IGF-1 using chemiluminescent immunometric assay Immulite. All data were analyzed using IBM SPSS ver. 24.0. The study has been approved by local Institutional Review Board with ethical clearance number 2017.02.1.0356. Results: Our study involved 44 MB and 2 PB leprosy. The common age group affected was between 31∼40 years old (23.9%), male (60.9%), and normal body mass index (BMI) (65.2%). Mean plasma IGF-1 level in PB leprosy was higher (91.07±0.74 ng/ml) than MB (82.74±6.44 ng/ml). The mean IGF-1 level decreases as BI increases in both groups (CI 95%=81.16∼85.04; p＜ 0.001). Pearson correlation test shows strong negative correlation (Pearson r=−0.976; p＜0.001) with determinant coefficient (R2) showing 95.2% (p＜0.001). Conclusion In Balinese leprosy patients, severity of disease status measured by BI were found to be strongly correlated with the plasma IGF-1 level which may help preventing transmission in household contacts by improving nutritional status.