Assessment of Serum Small Mothers Against Decapentaplegic 2 (SMAD2) in Type 2 Diabetic Patients with Early and Chronic Diabetic Nephropathy

Abstract

Background: Diabetic nephropathy (DN) is one of the most frequent and severe complications of diabetes mellitus and is associated with increased morbidity and mortality in diabetic patients. Transcription factor small mothers against decapentaplegic (Smad) family has key roles in cell fate decision in transmitting extracellular signals to the nucleus through transforming growth factor beta(TGF-β) receptors to activate downstream target gene transcription(Gomes et al., 2021). Smad proteins are a group of molecules that function as intracellular signal transducers downstream of the receptors of the TGF-b superfamily. The goal of this study is to investigate the diagnostic utility of Serum Small Mothers Against Decapentaplegic 2 (SMAD2) as a predictor biomarker in Type 2 Diabetic Patients with Early and Chronic Diabetic Nephropathy. The current study was designed as case control study, involved 120 individuals, 60 patients with type 2 diabetes mellitus (T2DM) group and 60 participants who are apparently healthy was used as control group. The patients group were subdivided into three equal groups according to their urinary albumin to creatinine ratio (ACR): 20 Type 2 Diabetic patients with normoalbuminuria; included patients with urinary albumin to creatinine ratio (uACR) <30 mg/g creatinine, 20 Type 2 Diabetic patients with microalbuminuria; included patients with urinary albumin to creatinine ratio (uACR) = 30-299 mg/g creatinine, Type 2 Diabetic patients with macroalbuminuria; included patients with urinary albumin to creatinine ratio (uACR) more than 300 mg/g. The results of the present study found that the Serum SMAD2 levels in T2DM with macroalbuminuria and in T2DM with microalbuminuria were much higher than T2DM with normoalbuminuria and control groups with highly statistically significant difference (P-value <0.001). Also, serum SMAD2 showed a positive correlation with ACR (r=0.703, P=0.001) and serum creatinine(r=0.673, P=0.001).So SMAD2 revealed a good diagnostic profile with sensitivity 66.70 %, specificity 90 %, positive predictive value (PPV) 91%, negative predictive value (NPV) 39%, and accuracy 63 % at a cutoff value of 2.995 ng/ml. In conclusion, this study revealed the importance of Small Mothers Against Decapentaplegic 2 (SMAD2) as a predictor for early stages of DN in T2DM which is powered by their correlation with albuminuria and it's high specificity and sensitivity through ROC analysis