High glucose load and endotoxemia among overweight and obese Arab women with and without diabetes: An observational study

Adipokines and Bacterial Metabolites: A Pivotal Molecular Bridge Linking Obesity and Gut Microbiota Dysbiosis to Target

Adipokines are essential mediators produced by adipose tissue and exert multiple biological functions. In particular, adiponectin, leptin, resistin, IL-6, MCP-1 and PAI-1 play specific roles in the crosstalk between adipose tissue and other organs involved in metabolic, immune and vascular health. During obesity, adipokine imbalance occurs and leads to a low-grade pro-inflammatory status, promoting insulin resistance-related diabetes and its vascular complications. A causal link between obesity and gut microbiota dysbiosis has been demonstrated. The deregulation of gut bacteria communities characterizing this dysbiosis influences the synthesis of bacterial substances including lipopolysaccharides and specific metabolites, generated via the degradation of dietary components, such as short-chain fatty acids, trimethylamine metabolized into trimethylamine-oxide in the liver and indole derivatives. Emerging evidence suggests that these bacterial metabolites modulate signaling pathways involved in adipokine production and action. This review summarizes the current knowledge about the molecular links between gut bacteria-derived metabolites and adipokine imbalance in obesity, and emphasizes their roles in key pathological mechanisms related to oxidative stress, inflammation, insulin resistance and vascular disorder. Given this interaction between adipokines and bacterial metabolites, the review highlights their relevance (i) as complementary clinical biomarkers to better explore the metabolic, inflammatory and vascular complications during obesity and gut microbiota dysbiosis, and (ii) as targets for new antioxidant, anti-inflammatory and prebiotic triple action strategies.

Genetic Variants of HNF4A, WFS1, DUSP9, FTO, and ZFAND6 Genes Are Associated with Prediabetes Susceptibility and Inflammatory Markers in the Saudi Arabian Population

Prediabetes is a reversible, intermediate stage of type 2 diabetes mellitus (T2DM). Lifestyle changes that include healthy diet and exercise can substantially reduce progression to T2DM. The present study explored the association of 37 T2DM- and obesity-linked single nucleotide polymorphisms (SNPs) with prediabetes risk in a homogenous Saudi Arabian population. A total of 1129 Saudi adults [332 with prediabetes (29%) and 797 normoglycemic controls] were randomly selected and genotyped using the KASPar SNP genotyping method. Anthropometric and various serological parameters were measured following standard procedures. Heterozygous GA of HNF4A-rs4812829 (0.64; 95% CI 0.47–0.86; p < 0.01), heterozygous TC of WFS1-rs1801214 (0.60; 95% confidence interval (CI) 0.44–0.80; p < 0.01), heterozygous GA of DUSP9-rs5945326 (0.60; 95% CI 0.39–0.92; p = 0.01), heterozygous GA of ZFAND6-rs11634397 (0.75; 95% CI 0.56–1.01; p = 0.05), and homozygous AA of FTO-rs11642841 (1.50; 95% CI 0.8–1.45; p = 0.03) were significantly associated with prediabetes, independent of age and body mass index (BMI). Additionally, C-reactive protein (CRP) levels in rs11634397 (AA) with a median of 5389.0 (2767.4–7412.8) were significantly higher than in the heterozygous GA genotype with a median of 1736.3 (1024.4–4452.0) (p < 0.01). In conclusion, only five of the 37 genetic variants previously linked to T2DM and obesity in the Saudi Arabian population [HNF4A-rs4812829, WFS1-rs1801214, DUSP9-rs5945326, ZFAND6-rs11634397, FTO-rs11642841] were associated with prediabetes susceptibility. Prospective studies are needed to confirm the potential clinical value of the studied genetic variants of interest.

Patterns of essential trace elements (Cr, Mn, Ni, and Se) in Saudi patients with type 2 diabetes mellitus

OBJECTIVES

Type 2 diabetes mellitus (T2DM) outcomes were observed to be influenced by circulating trace elements' status. The differences and correlations between serum levels of chromium (Cr), manganese (Mn), nickel (Ni), and selenium (Se) in Saudi patients with and without T2DM as well as those with prediabetes (pre-DM) were examined in this retrospective cross-sectional study.

METHODS

Anthropometrics and fasting blood samples were collected from 119 patients with T2DM (aged 41-64 years), 95 non-T2DM (aged 27-55 years), and 80 with pre-DM (aged 35-57 years). An inductively coupled plasma-mass spectrometer was used to measure trace minerals in the blood.

RESULTS

T2DM patients had significantly lower Mn serum concentrations than controls. There was no difference in Cr and Ni levels between groups. Serum Mn and Ni levels were lower in pre-DM subjects than controls. Serum Se concentrations were higher in pre-DM and T2DM patients than controls. In T2DM patients, serum Cr and Mn levels were inversely correlated with glucose, while Ni and Se levels were positively correlated with glucose in the T2DM group.

CONCLUSIONS

Because of their roles in glucose metabolism, impaired trace element status may also play a role in T2DM pathogenesis. Appropriate dietary control and mineral supplementation are recommended.

Circulating hepcidin and its associations with low-grade inflammation and iron indices among Arab adults with and without T2DM

We investigated the correlations of serum and dietary intake of iron with low-grade inflammation as well as with circulating hepcidin in adult Arabs with or without type 2 diabetes mellitus (T2DM). Three hundred and twelve (N=312) Saudi adult males and females with a mean age of 56.3 ± 6.5 years were included and divided into two groups, the control group (n=151, 43 males, 108 females), and T2DM group (n=161, 58 males, 103 females). Data included demographic characteristics, medical history, and dietary intake using food frequency and a 24-hour dietary recall for 1 day. Anthropometric measurements were noted and fasting blood samples extracted for the analysis of glucose, lipids, iron indices, hepcidin, 25(OH)D and endotoxin using commercially available assays. Hepcidin levels among T2DM participants were significantly higher than the control group (P<0.001). In all participants, serum hepcidin was positively associated with WHR, HbA1c, TG and TSAT while inversely associated with LDL-C and ferritin. Using hepcidin as dependent variable and age, anthropometrics, blood pressure, glucose, lipids, 25(OH)D, serum iron, transferrin and ferritin as independent variables showed that only glucose and WHR significantly predicted hepcidin by as much as 33.5% of the variances perceived (P<0.001). Sub-analysis in female participants revealed that endotoxin, iron and 25(OH)D were significant predictors of hepcidin, predicting 26.8% of the variances perceived (P<0.001). To conclude, the present study suggests that hepcidin is significantly linked with major cardiometabolic parameters, while its influence in iron indices, including low grade inflammation, appears to be stronger in females.

Endotoxemia, vitamin D and premature biological ageing in Arab adults with different metabolic states

There are limited studies on the association of endotoxin, a potent mediator of gut-derived inflammation and telomere length (TL). We investigated (1) the influence of adiposity on endotoxin and TL amongst Saudi adults according to type 2 diabetes mellitus (T2DM) status and (2) the influence vitamin D may have on TL attrition. Anthropometric data and fasting blood samples were taken from 775 Saudi adults visiting different primary care centers in Riyadh [387 T2DM and 388 non-T2DM]. TL, derived from peripheral blood mononuclear cells, was analyzed by Quantitative real-time polymerase chain reaction and circulating endotoxin levels by Limulus Amebocyte Lysate assay. Subjects were stratified based on obesity and T2DM status. A significant lower TL was observed in the non-obese T2DM group as compared with their non-obese, non-T2DM counterparts (p = 0.002). Significant inverse associations between TL, endotoxin and endotoxin activity were observed in the cohort with obesity. Regression analysis showed that endotoxin was a significant predictor for TL in all subjects and even after stratification according to subgroups; with variances perceived in circulating TL stronger among non-T2DM obese (10%; p = 0.003) than non-T2DM non-obese (12%; p = 0.007). Also, in the non-T2DM group, TL and HDL-cholesterol predicted 29% of the variances perceived in 25(OH)D (p < 0.001). Taken together these findings show that circulating endotoxin and 25(OH)D are associated with premature biological ageing influenced by adiposity and metabolic state; suggesting future intervention studies to manipulate gut microbiome and or vitamin D levels may offer ways to mitigate premature TL attrition.

Hepatokines Fetuin-A and Fetuin-B status in obese Saudi patient with diabetes mellitus type 2

The present study aims to investigate the association of the serum levels of Fetuin-A and Fetuin-B with type 2 diabetes mellitus (T2DM) in obese Saudi patients and explore the mechanism that links obesity and T2DM in Saudi patients. In this study, a total of 240 adult Saudis (116 men and 124 women) in the age group of 42.7±11.6 years were divided into three groups based on fasting blood glucose (FBG) levels: controls, T2DM and prediabetic. The levels of FBG, lipid profile and serum insulin were measured. Enzyme-linked immunosorbent assay (ELISA) was done to measure Fetuin-A, Fetuin-B and C-reactive protein (CRP). The results show that participants of the prediabetic and T2DM groups had significantly higher body mass index (BMI) values and elevated blood pressure (BP), FBG, total cholesterol (TC), triglyceride (TG), insulin, homeostatic model assessment-IR (HOMA-IR) and homeostatic model assessment-β (HOMA-β) as compared to the control group (P<0.001). The T2DM group participants exhibited significantly higher BMI, BP, FBG, TG, insulin, HOMA-IR and HOMA-β as compared to the prediabetic group participants (P<0.001). The serum levels of high-density lipoprotein-cholesterol (HDL-C) and low-density lipoprotein-cholesterol (LDL-C) were not significantly different among the three tested groups. The serum concentrations of CRP, Fetuin-A and Fetuin-B were slightly higher in T2DM patients as compared to the control group, but the difference failed to reach statistical significance (P>0.05). When results were segregated according to gender, FBG and HDL-C were significantly elevated (P=0.043 and P=0.002, respectively) in T2DM women (12.6±3.6 mmol/l and 1.0±0.3 mmol/l, respectively) compared to T2DM men (11.0±3.3 mmol/l and 0.86±0.2 mmol/l, respectively). However, the diastolic BP and waist-hip ratio (WHR) were significantly increased (P=0.010 and P=0.006, respectively) in T2DM men. The BMI and TC and all other measured parameters were similar between the two genders. Fetuin-A was significantly and positively associated with insulin levels (R=0.19, P=0.05), HOMA-IR (R=0.25, P=0.01) and TG (R=0.20, P=0.01) among overall participants of this study. The T2DM participants exhibited a significantly positive correlation with body weight. Fetuin-A was significantly and positively correlated with Fetuin-B in prediabetic participants, but this relation was not observed in the T2DM participants. Fetuin-B correlated inversely (P<005) with systolic BP (R=-0.20, P=0.01) and diastolic BP (R=-0.18, P=0.05). Interestingly, a strong inverse correlation was observed between Fetuin-B and TG in overall participants (R=-0.21, P=0.01) and specifically in T2DM women (R=-0.41, P=0.01). In conclusion, our study did not find a significant association of Fetuin-A or Fetuin-B levels in serum with T2DM. However, our results suggest that Fetuin-A may influence insulin resistance and serum Fetuin-B concentrations were inversely associated with TG in the general adult Saudi population.