Reference Interval of Homeostasis Model Assessment- Insulin Resistance in an Iraqi Adult Population: A Study in Nineveh Governorate

Abstract

Background: Insulin resistance (IR) is a condition in which the tissues become less responsive to insulin. IR has been linked to many diseases including Type 2 Diabetes Mellitus (T2DM), pre-diabetes, and metabolic syndrome. The most commonly used tool of IR assessment is Homeostasis Model Assessment of insulin resistance (HOMA-IR). In Iraq, there is limited data on the reference interval of HOMA-IR. Objectives: To calculate the reference interval of HOMA-IR among a randomly screened sample of adult people in Nineveh Province, Northern Iraq. Methods: This is a cross-sectional study that finally involved 286 apparently healthy adults (≥25 years). Data were collected in the period from the 1st of September to the end of December 2024. Weight and height were measured and body mass index (BMI) was calculated for each participant. Fasting serum insulin and glucose were tested and used to calculate HOMA-IR. Results: The overall mean ±SD of HOMA-IR for the study population was 2.11±1.34. HOMA-IR 95% reference interval was calculated based on the 2.5th percentile and 97.5th percentile after removing outliers and was (0.53- 4.32). The participants were then divided according to BMI into 3 groups. For subjects with BMI below 25 Kg/m2 , the mean HOMA-IR was 1.62±1.2, and the 95% reference interval was (0.46-3.54). For Subjects with BMI from 25- 29.99 Kg/m2 , the mean HOMA-IR was 1.88±0.75 and the reference interval was (0.64-4.04), however, for subjects with BMI ≥ 30 Kg/m2 , the mean ±SD of HOMA-IR was 2.71±1.61 and the reference interval was established to be (0.49-4.75). Conclusions: The upper end of the reference interval in our study was a bit lower than previous studies in Iraq, and comparable to other studies in the region. Higher BMI is associated with increase in the mean HOMA-IR (p < 0.000). The differences in the methods used to obtain HOMA-IR reference interval may lead to significantly different results.