Associations between serum adipocytokines and glycemic tolerance biomarkers in a rural Chinese population

Altered Red Blood Cell Fatty Acid and Serum Adipokine Profiles in Subjects with Obesity

BACKGROUND

Adipokines, as well as the fatty acid profile of red blood cell (RBC) membranes, are known to play important roles in the development and progression of metabolic complications induced by obesity. Thus, the objective of this study is to compare the serum adipokine profile and the RBC membrane fatty acid profile of normal-weight and obese adults, and to analyze their relationship with serum biochemical parameters.

METHODS

An observational case-control study was performed in 75 normal-weight and obese adult subjects. Biochemical serum parameters, eight serum adipokines and the RBC membrane fatty acid profiles were measured. Associations between parameters were established using regression analysis.

RESULTS

Subjects with obesity showed increased levels of leptin, fibroblast growth factor 21 (FGF21) and overexpressed nephroblastoma (NOV/CCN3), decreased adiponectin, and similar levels of vaspin and chemerin compared to normal-weight subjects. Significant positive and negative correlations were found with triglycerides and high-density lipoprotein-cholesterol (HDL-c), respectively. An increase in the total ω-6 fatty acids in the RBC membrane fatty acid profiles in subjects with obesity was observed, because of higher levels of both dihomo-γ-linolenic acid (DGLA) and arachidonic acid (AA), and decreased total ω-3 fatty acids, mainly due to lower levels of docosahexaenoic acid (DHA). The ω-6/ω-3 ratio in the RBCs was significantly higher, suggesting an inflammatory status, as was also suggested by a reduced adiponectin level. A negative association between DGLA and adiponectin, and a positive association between DHA and serum triglycerides, was observed.

CONCLUSIONS

Important alterations in serum adipokine and RBC fatty acid profiles are found in subjects with obesity.

Association of Non-Insulin-Based Insulin Resistance Indices with Risk of Incident Prediabetes and Diabetes in a Chinese Rural Population: A 12-Year Prospective Study

OBJECTIVE

Three non-insulin-based insulin resistance (IR) indices, ie, triglyceride-glucose (TyG) index, triglyceride-to-high-density lipoprotein cholesterol (TG/HDL-C) ratio, and metabolic score for IR (METS-IR), were considered powerful and simplified alternatives for IR. However, evidence for the association between the three IR indices and incident type 2 diabetes mellitus (T2DM), especially impaired fasting glucose (IFG), remains limited. Therefore, this study aimed to explore the association among IR indices, incident IFG, and T2DM in a rural population cohort.

METHODS

We analyzed data from 2209 adults (aged 24-75 years) at baseline and from 1205 normoglycemic participants who were followed up. Cox proportional hazards models were used to evaluate the associations between the three indices and IFG or T2DM. Restricted cubic spline curves based on the Cox regression model were used to examine the association between baseline indices and incident T2DM.

RESULTS

For the baseline data, logistic analyses demonstrated that the TyG index, TG/HDL-C ratio, and METS-IR had a significantly positive correlation with IFG or T2DM after multivariable adjustment. During a median follow-up of 12.17 years, 157 incident cases of IFG and 97 incident cases of T2DM were noted. The risk of T2DM, but not IFG, was strongly associated with the baseline TyG index in the adjusted model, and participants with the TyG index in the third tertile had a higher risk of developing T2DM (adjusted hazards ratio, 2.84; 95% confidence intervals, 1.26-6.37; p for trend <0.001) than those in the lowest tertile (reference). Moreover, a linear relationship was observed between the TyG index and T2DM incidence. The TG/HDL-C ratio and METS-IR had no significant relationship with the risk of IFG or T2DM.

CONCLUSION

The TyG index is more useful than the TG/HDL-C ratio and METS-IR in predicting T2DM in the normoglycemic population.

Inflammatory biomarkers and prediction of insulin resistance in Congolese adults

Several studies have shown that low levels of adiponectin (ADP) and high levels of alpha tumor necrosis factor (NFT) increase the risk or severity of many cardiometabolic diseases associated with insulin resistance. The main objective of this study was to evaluate the association between plasma adipokines and IR measured by HOMA-IR. The secondary objective was to determine the biomarker of the potential inflammation to predict IR in Congolese melanoderm subjects residing in Brazzaville. This cross-sectional study was conducted on 234 apparently healthy participants over the age of 18. Socio-demographic and clinical data were collected. Biological data, including the total ADP and NFT dosage, were measured using the ELISA method. Participants were categorized into two groups according to HOMA-IR ≥ 2.5. Univariate and multivariate logistic regression analyses were conducted to identify risk factors for insulin resistance. An optimized model was obtained after the logistic regression. The analysis of the receptor's operating characteristics (OCR) was performed to determine the optimal threshold value and diagnostic characteristics, as well as the area under the curve (ASC). ADP averages were significantly low (11.49 ± 7.61 ng/mL; P < 0.001) while those of TNF were significantly higher (96.03 ± 44.09 pg/mL) in the HOMA-IR group ≥ 2.5. There was a positive and significant correlation (p < 0.05) between BMI, TT, CRPhs, TNF and HOMA-IR. And a negative and significant correlation was noted between ADP and HOMA-IR (r = - 0.39; P < 0.01). Similarly, a negative and significant correlation (p < 0.01) was noted between BMI, TT, TNF, CRPhs and ADP. The optimal threshold value of the total ADP for predicting IR was 17.52 ng/mL with a sensitivity of 89% [IC 95% (0.83-0.95)], 56% specificity [IC 95% (0.47-0.65)] and a CSA of 0.76 [IC 95% (0.69-0.81)]. After logistic regression, the CSA of the optimized model was 0.84 [IC 95% (0.79-0.89)]. ADP can be used as a highly plausible IR prediction biomarker.

Plasma Lipocalin-2 and Adiponectin are Affected by Obesity Rather Than Type 2 Diabetes Mellitus per se

PURPOSE

Changes in plasma adipocytokines and inflammatory markers in type 2 DM remain controversial as to whether they are due to obesity or directly associated with the diabetic state. Our objective was to study the effect of obesity and diabetes on plasma lipocalin-2 (LCN2), adiponectin, and interleukin-1β (IL-1β) by comparing their levels in non-diabetic obese subjects and non-obese type 2 DM patients, as well as determining the association of these adipocytokines with metabolic syndrome factors and diabetic parameters.

PATIENTS AND METHODS

In this study, 85 Yemeni male volunteers aged 30-60 years old were enrolled, 25 of whom were healthy subjects with BMI < 25 kg/m² served as control; 30 non-diabetic obese subjects (BMI ≥ 30 kg/m² and FBG < 6.1 mmol/l); and 30 non-obese type 2 DM patients (BMI < 25 kg/m² and FBG > 7 mmol/l).

RESULTS

Lipocalin-2 and adiponectin were significantly (p = 0.043 and p = 0.034) lower in non-diabetic obese subjects by 16.2% and 29.7% with respect to control group, with no effect in the non-obese type 2 DM patients. Moreover, LCN2 was significantly (p = 0.04) lower in the non-diabetic obese subjects by 15.8% as compared with the non-obese type 2 DM patients, with no significant difference in adiponectin levels. In contrast, serum IL-1β was significantly (p = 0.001 and p = 0.003) higher in both non-diabetic obese subjects and the non-obese type 2 DM patients by 76.5% and 67.7% as compared to control group. The significant decrease in both LCN2 and adiponectin and the significant increase in IL-1β in the non-diabetic obese subjects disappeared upon adjustment for waist circumference (WC). In contrast, the significant increase in IL-1β in the non-obese Type 2 DM patients was not affected upon adjustment for WC.

CONCLUSION

Plasma LCN2 and adiponectin were not affected by diabetes per se, suggesting that the observed changes in LCN2 and adiponectin in type 2 DM may be due to obesity rather than the diabetic state, whereas IL-1β levels were affected by both obesity and diabetes.

Serum leptin in male hypothyroid prediabetic patients: Association with cardiovascular risk

Introduction

Hyperliptenemia is a risk factor for coronary heart disease (CHD). Hypothyroidism and prediabetes confer an increased cardiovascular risk. Few studies have addressed the role of leptin in hypothyroid prediabetic patients and its effect on CHD risk factors.

Objective

The aim of this study was to detect serum levels of leptin in hypothyroid prediabetic patients and their relationship with risk factors for CHD.

Patients and methods

The study included three groups; group A included 120 hypothyroid male patients with normal glucose tolerance, group B included 120 hypothyroid male patients with prediabetes, and group C included 120 healthy individuals matched for age and sex as a control group. All groups were subjected to assessment of history, clinical examination, and laboratory investigations including fasting and 2 h postprandial blood glucose, serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), free T3, free T4, thyroid-stimulating hormone, and fasting serum leptin.

Results

Serum leptin was significantly higher in groups A and B compared with group C (P=0.0001), whereas there was no significant difference in serum leptin between groups A and B. In comparison with group A, the patients in group B had significantly higher serum TC (P=0.02), LDL (P=0.04), and lower serum HDL (P=0.02). In group B, serum leptin correlated positively with serum TC (P=0.0001), TG (P=0.041), and LDL (P=0.036), and negatively with serum HDL (P=0.039).

Conclusion

Hypothyroidism is associated with high serum leptin independent of prediabetic state. Serum leptin in hypothyroid prediabetic patients showed a direct relationship with some primary markers of metabolic syndrome; thus, leptin may predict the development of CHD in those patients.