Vol. 7, Issue 2, Part D (2025)

Background and Objectives: Prediabetes represents an intermediate state between normoglycemia and type 2 diabetes mellitus (T2DM), with high risk of progression to overt diabetes. Vitamin D deficiency has been linked to impaired insulin secretion, increased insulin resistance, and glucose intolerance. While the relationship between vitamin D status and insulin resistance in diabetic patients has been documented, evidence in prediabetic individuals remains limited. The present study aimed to evaluate the association between serum 25(OH) vitamin D and insulin resistance among prediabetic individuals.
Materials and Methods: This cross-sectional observational study was conducted at Mediciti Institute of Medical Sciences, Hyderabad, India. A total of 100 individuals aged 25-50 years were included, comprising 50 prediabetic patients (cases) and 50 age- and sex-matched healthy controls. Prediabetes was defined as fasting plasma glucose (FPG) 100-125 mg/dl and/or 2-hour post-OGTT plasma glucose 140-199 mg/dl. Serum 25(OH) vitamin D levels and fasting insulin were measured; insulin resistance was calculated using HOMA-IR. Data were analyzed using unpaired Student’s t-test and Pearson’s correlation coefficient. A p-value <0.05 was considered statistically significant.
Results: The mean age, gender distribution, and BMI were comparable between groups. Hypovitaminosis D (<20 ng/ml) was observed in 66% of prediabetic individuals compared to 16% of controls. Prediabetic cases showed significantly higher FPG (100.24 ± 9.18 vs. 84.27 ± 7.44 mg/dl), 2-hour plasma glucose (153.87 ± 13.56 vs. 124.38 ± 11.46 mg/dl), insulin (18.26 ± 12.14 vs. 10.81 ± 8.29 μIU/ml), and HOMA-IR (5.32 ± 2.96 vs. 2.31 ± 2.01), and significantly lower serum 25(OH) vitamin D levels (14.88 ± 11.36 vs. 22.16 ± 8.47 ng/ml) compared to controls (all p<0.05). A significant inverse correlation was found between serum 25(OH) vitamin D and both HOMA-IR (r = -0.275, p=0.038) and fasting insulin (r = -0.268, p=0.029), while correlations with FPG and 2-hour plasma glucose were not significant.
Conclusion: Vitamin D deficiency is highly prevalent in prediabetic individuals and is significantly associated with insulin resistance. These findings suggest that hypovitaminosis D may contribute to the pathogenesis of insulin resistance in prediabetes, highlighting the potential role of vitamin D status as a modifiable factor in early prevention of diabetes.