Postprandial lipemia and its relation to TCF7L2 gene polymorphisms in normoglycemic first-degree relatives of type 2 diabetes patients

Correlation between TCF7L2 gene expression and certain biochemical parameters in type 2 diabetes mellitus

Objectives

The transcription factor 7-like 2 gene (TCF7L2) is associated with a predisposition to type 2 diabetes mellitus (T2DM) in different ethnic populations. This article investigated the relationship between TCF7L2 gene expression and several biochemical indexes among different age categories of T2DM in a sample of the Iraqi population.

Methods

One hundred and fifty blood samples were collected from three groups: young T2DM (10-35 years), old T2DM (40-80 years), and healthy control (10-65 years) groups. Both sexes were enrolled. qPCR was performed to explore the expression of the TCF7L2 gene. Biochemical tests were performed to assess hemoglobin A1C (HbA1c), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels. The body mass index (BMI) was calculated. The results were statistically analyzed.

Results

Patients with T2DM had higher BMI, TG, and LDL, and lower HDL than the control group. There was a strong positive correlation between hemoglobin A1C (HbA1c) and BMI, TG, and LDL and a negative correlation between HbA1c and HDL. Expression of the TCF7L2 gene showed a significant difference between old and young patients by 1.68 and 0.207 fold, respectively. These results showed that old patients had higher gene expression than young patients.

Conclusion

TCF7L2 gene expression was affected by age, with higher expression in old T2DM patients. This may influence beta cell functions and insulin secretion.

TCF7L2 gene associated postprandial triglyceride dysmetabolism- a novel mechanism for diabetes risk among Asian Indians

AIM

TCF7L2 gene is believed to increase the risk of T2DM by its effects on insulin secretion. However, the exact mechanism of this enhanced risk is not clearly known. While TCF7L2 gene has been shown to affect lipid metabolism, these effects have remained largely unexplored in the context of diabetes risk.

METHODS

Postprandial lipid responses to a standardized fat challenge test were performed in 620 Asian Indian subjects (310 with NGT and 310 with T2DM/prediabetes) and compared between the risk and wild genotypes of the rs7903146 TCF7L2 gene. In 30 subjects scheduled to undergo abdominal surgery (10 each with NGT, Prediabetes and T2DM), adipocyte TCF7L2 gene expression was also performed by real time qPCR and confirmed by protein expression in western blot.

RESULTS

T allele of rs7903146 TCF7L2 gene was confirmed as the risk allele for T2DM (OR=1.8(1.2-2.74), p=0.005). TT+CT genotypes of rs7903146 TCF7L2 gene showed significantly higher 4hrTg (p<0.01), TgAUC (p<0.01), peakTg (p<0.01) as well as higher postprandial plasma glucose (p=.006) levels and HOMA-IR (p=0.03) and significantly lower adiponectin levels (p=0.02) as compared to CC genotype. The expression of TCF7L2 gene in VAT was 11-fold higher in prediabetes group as compared to NGT (P<0.01) and 5.7-fold higher in T2DM group as compared to NGT group(P=0.003) and was significantly associated with PPTg and glucose levels.

CONCLUSION

There is significant PPTg dysmetabolism associated with the risk allele of rs7903146 polymorphism as well as adipocyte expression of TCF7L2 gene. Significant upregulation of TCF7L2 gene expression in VAT that correlates with PPTg and glycaemia is also seen in Asian Indians with glucose intolerance. Modulation of PPTg metabolism by TCF7L2 gene and the resultant PPHTg may be a novel mechanism that contributes to its diabetes risk in them.

Adipose tissue expression of UCP1 and PRDM16 genes and their association with postprandial triglyceride metabolism and glucose intolerance

AIMS

UCP1 and PRDM16 genes, primarily involved in browning of adipose tissue that can affect lipid metabolism are also associated with diabetes risk. Therefore, we planned to study the adipose tissue expression of UCP1 and PRDM 16 genes in subjects with glucose intolerance to find out its association with postprandial triglyceride (PPTg) measures and T2DM.

METHODS

A total of 30 subjects were recruited in three groups i.e., NGT, prediabetes and T2DM (NDDM + known T2DM) who were matched for age, sex and BMI. An 8-hour standardized fat challenge test was performed to study lipemic responses. UCP1 and PRDM16 genes quantification in adipose tissue was performed by real-time PCR followed by SDS PAGE.

RESULTS

UCP1 gene expression in SAT was significantly lower in T2DM and prediabetes as compared to NGT group while PRDM16 gene expression was significantly lower in T2DM group as compared to NGT group. UCP1 gene expression correlated with PPTg measures as well as with glycaemic measures while PRDM16 gene expression correlated with glycaemic measures only.

CONCLUSION

This study found downregulation of PRDM16 and UCP1 gene expression in SAT in subjects with glucose intolerance. The association of UCP1 gene expression with PPTg dysmetabolism may contribute to greater predisposition to T2DM.

Effect of postprandial triglycerides on DDT/ppDDE levels in subjects with varying degree of glucose intolerance

BACKGROUND

Organochlorine pesticides such as DDT as well as postprandial hypertriglyceridemia have been linked with insulin resistance and diabetes mellitus. The cardiometabolic risk of PPhTg could also be due to its potential to increase the serum levels of this highly lipophilic pesticide. We studied the effect of postprandial triglyceride responses to a standard oral fat challenge on the levels of DDT and its metabolites in subjects with varying degree of glucose intolerance METHODS: A standard fat challenge was performed in 60 subjects who were categorized as NGT, prediabetes, and NDDM based on an earlier OGTT. Fasting and postprandial levels of serum triglycerides, plasma DDT and its metabolites were estimated and compared in the 3 groups and their association with each other, and measures of glycemia and insulin resistance were also determined.

RESULTS

Peak Tg and TgAUC levels were significantly higher in NDDM group as compared to NGT and PD groups. TgAUC showed positive correlation with fasting plasma glucose (r=0.33, p=0.01), postprandial plasma glucose (r=0.39, p=0.002) and HOMA IR(r=0.63, p=0.001). ppDDE levels were found to be significantly higher in NDDM subjects compared with NGT group. ppDDE-AUC was significantly higher in the NDDM group compared with the other two study groups. Mean ppDDE levels also showed strong positive correlation with peak Tg (r=0.295 p=0.022), TgAUC (r=0.303 p=0.018), iPPTgAUC(r=0.57 p≤0.001) and iPPpeakTg(r=0.51 p≤0.001) as well as with FPG (r=0.269 p=0.038) PPPG (r=0.424 p=0.001) and HbA1c (r=0.321 p=0.012).

CONCLUSION

The findings of this study support the concept that the cardiometabolic risk associated with PPhTg may at least in part be related to the associated increase in serum levels of lipophilic OCPs like DDT.