Serum levels of nitric oxide and its correlation with endothelial nitric oxide synthase gene expression among type 2 diabetic patients with or without hypertension: A comparative study in a tertiary care hospital of North East India

Background: The serum nitric oxide (NO) data in Type 2 diabetes mellitus (T2DM) patients reported by different scientific literature are controversial. Some research articles reported increased NO levels in diabetes patients, whereas others reported the opposite. Hence, this study was designed to compare the serum NO levels in T2DM patients with or without hypertension among subjects reporting to the Diabetes Nutrition Clinic (DNC) of a tertiary care hospital of Tripura. Aims: The aim of this study was to estimate serum levels of NO among Type 2 diabetic patients with or without hypertension, to determine the endothelial NO synthase (eNOS) gene expression at the transcriptional level, and also to assess the correlation between serum NO and eNOS gene expression among the study subjects. Materials and Methods: This hospital-based cross-sectional study was conducted from March 2019 to February 2020 among 198 diabetic patients attending the DNC of a tertiary care hospital of Tripura. Estimation of serum NO was performed using the ELISA technique and eNOS gene expression was performed using the reverse transcription-polymerase chain reaction technique. All statistical analysis was done using SPSS software version 25. Results: This study was conducted among 98 type 2 diabetic patients having hypertension and 100 controls, i.e., type 2 diabetics without hypertension. The mean serum level of NO in diabetic patients with hypertension was 35.35 ± 13.65 μmoles/L, whereas in the control group, i. e., diabetic patients without hypertension, it was 89.83 ± 10.29 μmoles/L, which was statistically significant (P < 0.001). A significant correlation (P < 0.001) was also found between serum NO level and eNOS gene expression among the study subjects. Conclusion: In conclusion, significantly higher serum NO levels were observed among the T2DM patients without hypertension as compared to the T2DM patients having hypertension.