Growth Differentiation Factor-15 as a Biomarker of Obese Pre-diabetes and Type 2 Diabetes Mellitus in Indian Subjects: A Case-control Study

Type 2 diabetes mellitus (T2DM) is an ever-growing epidemic in India and poses significant morbidity, mortality, and socioeconomic burden.Growth differentiation factor-15 (GDF15) is a stress-responsive cytokine, increased in T2DM patients compared to control subjects without the disease. We aimed to assess whether serum GDF15 and adipose tissue GDF15 expression can differentiate between obese pre-diabetes and T2DM and control populations.We recruited 156 individuals including 73 type 2 diabetes, 30 pre-diabetes, and 53 healthy controls. Clinical history, anthropometric measurements and biochemical profiling were taken. Insulin resistance indices were calculated following HOMA models. Serum GDF15 was measured by sandwich ELISA. Visceral adipose tissue (VAT) expression of GDF15 was observed in 17 T2DM patients and 29 controls using SYBR Green chemistry in RT-PCR using GAPDH as the housekeeping gene. The data were analyzed on R programming platform using RStudio.Serum GDF15 was significantly higher (p<0.001) in T2DM subjects (median 1445.47 pg/mL) compared to pre-diabetes (627.85 pg/mL) and healthy controls (609.01 pg/mL). Using the ΔΔCt method, the VAT GDF15 expression was 1.54 fold and 1.57 fold upregulated in T2DM (n=17) compared to control subjects (n=29), and obese (n=12) compared to non-obese (n=34)subjects, respectively. The optimal cut-off point following Youden's index method was found to be 868.09 pg/mL. ROC curve analysis revealed that serum GDF15 had a sensitivity, specificity, and area under the curve (AUC) of 90.41%, 79.52%, and 0.892 respectively. GDF15 levels were significantly associated with age, BMI, HbA1c, fasting blood sugar, and insulin resistance indices.Hence, serum GDF15 is a biomarker for T2DM patients in our study population from Western India. However, larger prospective cohorts are necessary to validate this claim.