Diabetes mellitus incidence and prevalence are increasing worldwide because of growing rates of obesity, metabolic syndrome and westernization of lifestyle. Concurrently, the incidence of diabetic kidney disease (DKD) rises; DKD is widely regarded as the most serious complication of DM and a major cause of CKD. Between 20 and 50% of patients with T2DM will eventually develop DKD [21] Sestrin-2 belongs to a highly conserved family of stress responsive proteins with antioxidant characteristics. In order to preserve cellular survival and homeostasis, noxious environmental and metabolic stimuli such as oxidative stress, inflammation and DNA damage induce the expression of Sestrins. Additionally, Sestrin 2 suppresses the production of reactive oxygen species (ROS) [22].

In our study, significant low level of Sestrin 2 was found in the macroalbuminuric group as compared to the other two diabetic and control groups. Although it showed negative correlation with age, BMI, serum cholesterol and TG, it didn’t reach a significant level except for serum albumin. The cut off value of serum Sestrin 2 to predict DN was 0.98 ng/ml with sensitivity 99%, specificity 66%. In multiple linear regression of the predictor for DN where UACR was the dependent variable, Sestrin 2 was a non- significant predictor (P value = 0.177).

In hyperglycemic and dyslipidemic environments, Sestrin 2 controls monocyte activation and atherogenic events via the AMPK-mTOR nexus. Sundararajan S, et al., investigated the association between Sestrins levels and dyslipidemia, atherosclerosis and DM. The mRNA expressions of Sestrin1 and Sestrin3 in monocytes in dyslipidemic patients but not in diabetics was significantly reduced. However, Sestrin2 mRNA expression was significantly reduced in diabetics with and/or without dyslipidemia. This finding is consistent with our results. Additionally, glycemic and lipid parameters showed a negative correlation with the levels of sestrin2 mRNA [9].

According to Watany M et al., the degree of albuminuria is correlated with a decrease in Sestrin 2 gene expression and serum protein levels, with macroalbuminuria being associated with the lowest levels. When their results were subjected to multiple regression analysis for prediction of microalbuminuria, it was found that SESN2 expression (P value 0.019) but not serum Sestrin 2 (P 0.09) was able to predict it [23]. AMPactivated protein kinase (AMPK) effectively inhibits mTORC1 activity to regulate autophagy. Additionally, AMPK supports mitochondrial activity and has antioxidant characteristics. Sestrin 2 was found to improve the functions of mitochondria in podocytes and apoptosis through AMPK signaling as proved by Lin et al., They investigated the effects of Sestrin 2 on the regulation of AMPactivated protein kinase (AMPK) in streptozotocininduced diabetic rats and DN patients. They revealed that Sestrin 2 expression was decreased in hyperglycemic stimulated podocytes, as well as in diabetic rats and patients with DN [22].

However, in contrast to the healthy control group, Chung et al. observed that obese and T2DM patients had higher serum Sestrin 2 levels. Their results also were positively correlated with BMI, serum TG, glucose, C-reactive protein, and the degree of insulin resistance [12].

One of the angiopoietin family is Betatrophin (MW; 22 KDa); a circulating hormone derived from the liver that stimulates the proliferation of pancreatic β-cells and lipid metabolism. It is also referred to as lipasin, angiopoietin-like protein 8 (ANGPTL8), refeeding induced in fat and liver (RIFL), or hepatocellular carcinoma-associated gene TD26 [14]. Interest in betatrophin as a possible β-cell regenerative treatment for diabetes and subsequent DN has grown. Nevertheless, a number of subsequent investigations suggested that insulin and a high-fat diet may also induce the expression of betatrophin, leading to elevated serum TG and insulin resistance rather than enhanced glucose metabolism [24, 25].

Although type 2 diabetes patients’ resistance to the effects of betatrophin, cannot be ruled out, the results of this study revealed significant high level of betatrophin in the macroalbuminuric group as compared to the other two diabetic and control groups. (P value = 0.001) Serum betatrophin showed significant positive correlation with age, fasting, 2 h postprandial, BMI, TG, total cholesterol, serum creatinine, blood urea, UACR, and significant negative correlation with eGFR and serum albumin. Additionally, betatrophin and diabetic nephropathy were found to be significantly correlated using multiple linear regression. (P value = 0.001*)

Urinary albumin loss has been associated with insulin resistance, which in turn causes the production of hepatic hormones, that may act as mediators of the increased proliferation of B cells in T2DM. Numerous investigations showed that T2DM patients had elevated betatrophin levels. Chen et al. discovered that T2DM patients had significantly higher serum levels of betatrophin than did healthy subjects, particularly in the macroalbuminuria group. (P < 0.001). Serum betatrophin level showed an inverse correlation with eGFR, total cholesterol, and high-density lipoprotein cholesterol (HDL-C), but a positive correlation with sex, diabetes duration, systolic blood pressure (SBP), BMI, UACR, and TG. They concluded that albumin loss may result in increased betatrophin secretion [26] HbA1c, FBG, and TG were found to positively correlate with betatrophin levels by Maurer L et al. Moreover, age, SBP and intima media thickness were all positively correlated with betatrophin while CKD-EPI eGFR was negatively correlated [27].

According to Mohany et al.‘s results, the T2DM group’s serum betatrophin level was higher than that of the healthy control group, and the difference was greater in the macroalbuminuric group. Furthermore, our results were supported by the substantial positive correlations that were discovered in this study between the levels of serum betatrophin and BMI, HbA1C%, glycated albumin%, FBG, and creatinine [10].

In agreement to our results, Alshawaf et al., suggested betatrophin level as a risk predictor for DN in association with angiopoietin 2. The serum levels of Angiopoietin-like proteins (ANGPTL) 3, ANGPTL4, betatrophin, angiopoietin 1 and 2 were measured in 50 type 2 diabetic patients and 67 DN patients compared to 117 healthy participants. When Ang2 and ANGPTL8 were combined, the receiver operating characteristic (ROC) analysis yielded an area under the curve (AUC) of 0.77 and an 80.7% specificity for DN prediction [28].

Conversely, Javier Gómez-Ambrosi et al., discovered that betatrophin levels in the blood were much lower in obese people, and even lower in those with impaired glucose tolerance and T2D participants who had a noticeable sexual dimorphism. Furthermore, they showed that the levels of betatrophin in the blood were significantly greater in women than in men [29]. The differences between our findings and those of other researches on the levels of Sestrin 2 and betatrophin may be caused by various immunoassays, sample size or subject differences, particularly in terms of BMI and diabetes duration.

As a cross-sectional study, the sample size was comparatively small.