Association of C-peptide with diabetic vascular complications in type 2 diabetes

Fasting plasma C-peptide correlates with body mass index, hsCRP, apolipoprotein B, and other atherogenic lipids in healthy individuals

C-peptide has a complex role in human physiology, but its effects are not fully understood. Studies have shown a protective impact against diabetic complications, but also that C-peptide levels associate with cardiovascular events. Among the many applications to assess cardiovascular risk, circulating lipids are widely used, and one of the strongest biomarkers is apolipoprotein B. The aim of this investigation was to study the association of C-peptide with markers of metabolic, inflammatory, or cardiovascular alterations in a limited group of healthy individuals. Body mass index (BMI), lipids, and other plasma markers were studied in 28 consecutive healthy individuals within the age of 30-50 years. The results showed significant positive correlations between C-peptide and BMI (r = 0.498; p = 0.007); hsCRP (r = 0.530; p = 0.004); triglycerides (r = 0.530; p = 0.005); cholesterol (r = 0.507; p = 0.006), LDL-cholesterol (r = 0.550; p = 0.002), LDL/HDL ratio (r = 0.460; p = 0.014); apoB (r = 0.622; p < 0.001), apoB/apoA1 ratio (r = 0.563; p = 0.002); and non-HDL cholesterol (r = 0.566; p = 0.002). According to BMI values, 16 of the 28 individuals were overweight (BMI >25.0 kg/m2). If overweight individuals were excluded, C-peptide did only correlate with apoB (r = 0.636; p = 0.026). To conclude, C-peptide within normal levels associate with BMI and atherogenic lipids in healthy individuals, and apoB associate with C-peptide even at normal weight. These results suggest that C-peptide can be an early additional cardiovascular risk marker.

The small molecule peptide ANXA114-26 inhibits ovarian cancer cell proliferation and reverses cisplatin resistance by binding to the formyl peptide receptors receptor

Chemo-resistance in ovarian cancer is currently a major obstacle to the treatment and recovery of ovarian cancer. Therefore, identifying factors associated with chemo-resistance in ovarian cancer may reverse chemo-sensitization. Using isobaric tags for relative and absolute quantitation (ITRAQ) technology, we found a small molecule peptide with annexin 1 (ANXA1) as a precursor protein. Then, we explored the effects and mechanisms of this small molecule peptide on the proliferation, apoptosis, and drug resistance of ovarian cancer resistant cells through CCK-8, EdU cell proliferation assay, Annexin V-FITC/PI assay, Western blot,qRT-PCR. ANXA114-26 was highly expressed in the serums of sensitive patients. ANXA114-26 promoted apoptosis of ovarian cancer cells and increased the sensitization of ovarian cancer cells to cisplatin. The ANXA114-26 and ANXA1 competitively bind formyl peptide receptors (FPR). ANXA114-26 decreased multidrug resistance-associated protein 1 (MRP1) expression in ovarian cancer cells through the FPR/Cyclin D1/NF-ĸBp65 pathway. We found a peptide derived named ANXA114-26 in the serum of ovarian cancer patients. It can reduce ovarian cancer cell proliferation and reduce MRP1 expression through the FPR/Cyclin D1/NF-ĸBp65 pathway.

Elevated Fasting C-Peptide Levels Correlate with Increased 10-Year Risk of Atherosclerotic Cardiovascular Disease in Newly Diagnosed Type 2 Diabetes Patients

Purpose

This study aims to analyze the impact of serum C-peptide levels in patients with newly diagnosed type 2 diabetes (T2DM) on the 10-year risk of atherosclerotic cardiovascular disease (ASCVD).

Patients and Methods

A total of 1923 patients with newly diagnosed T2DM were selected and categorized into four groups based on the interquartile range of fasting C-peptide (FCP) levels: Q1 group (FCP≤0.568 ng/mL), Q2 group (0.568 < FCP≤0.751 ng/mL), Q3 group (0.751 < FCP≤0.980 ng/mL), and Q4 group (FCP > 0.980 ng/mL). Clinical data were collected, and the China-PAR model was employed to evaluate the risk score of ASCVD within 10 years. Additionally, the correlation between FCP levels and the risk of ASCVD was analyzed.

Results

As the quartiles of FCP increased, the 10-year ASCVD risk exhibited a gradual increase. The risk score in the FCP > 0.980 ng/mL group was significantly higher than that in the other groups, with noted differences related to gender and weight. Multiple linear regression analysis indicated that, even after adjusting for confounding factors such as gender, age, body mass index (BMI), and glycosylated hemoglobin, FCP levels remained a positive predictor of the 10-year ASCVD risk.

Conclusion

High FCP levels are identified as a risk factor for ASCVD within 10 years in patients with newly diagnosed T2DM.

Factors related to type 2 diabetic retinopathy and their clinical application value

Objective

To compare the differences in clinical-related factors between patients with type 2 diabetes (T2DM) and those without diabetic retinopathy (DR) and to explore the risk factors or protective factors affecting DR in T2DM patients.

Methods

We performed a retrospective analysis of 380 patients with type 2 diabetes admitted to Handan Central Hospital from June 2023 to May 2024. Clinical data collected included baseline characteristics, hematological tests, metabolic indicators, and information on diabetic complications and comorbidities.

Results

Our findings identified intervention, neck vascular disease, bilateral lower limb venous thrombosis, high creatinine, high glomerular filtration rate, high chloride, high fasting C-peptide, and high lactate dehydrogenase as risk factors for DR. In contrast, High 2-hour postprandial C-peptide is a protective factor for diabetic retinopathy. A logistic regression model was constructed using stepwise regression to predict DR occurrence, achieving an accuracy of 0.80 and an AUC of 0.83.

An enhanced machine learning algorithm for type 2 diabetes prognosis with a detailed examination of Key correlates

This study aimed to construct a high-performance prediction and diagnosis model for type 2 diabetic retinopathy (DR) and identify key correlates of DR. This study utilized a cross-sectional dataset of 3,000 patients from the People's Liberation Army General Hospital in 2021. Logistic regression was used as the baseline model to compare the prediction performance of the machine learning model and the related factors. The recursive feature elimination cross-validation (RFECV) algorithm was used to select features. Four machine learning models, support vector machine (SVM), decision tree (DT), random forest (RF), and gradient boost decision tree (GBDT), were developed to predict DR. The models were optimized using grid search to determine hyperparameters, and the model with superior performance was selected. Shapley-additive explanations (SHAP) were used to analyze the important correlation factors of DR. Among the four machine learning models, the optimal model was GBDT, with predicted accuracy, precision, recall, F1-measure, and AUC values of 0.7883, 0.8299, 0.7539, 0.7901, and 0.8672, respectively. Six key correlates of DR were identified, including rapid micronutrient protein/creatinine measurement, 24-h micronutrient protein, fasting C-peptide, glycosylated hemoglobin, blood urea, and creatinine. The logistic model had 27 risk factors, with an AUC value of 0.8341. A superior prediction model was constructed that identified easily explainable key factors. The number of correlation factors was significantly lower compared to traditional statistical methods, leading to a more accurate prediction performance than the latter.

Risk of Diabetic Retinopathy According to Subtype of Type 2 Diabetes

Type 2 diabetes is a heterogeneous disease that can be subdivided on the basis of β-cell function and insulin sensitivity. We investigated the presence, incidence, and progression of diabetic retinopathy (DR) according to subtypes of type 2 diabetes. In a national cohort, we identified three subtypes of type 2 diabetes: classical, hyperinsulinemic, and insulinopenic type 2 diabetes, based on HOMA2 measurements. From the Danish Registry of Diabetic Retinopathy we extracted information on level of DR. We used several national health registries to link information on comorbidity, medications, and laboratory tests. We found individuals with hyperinsulinemic type 2 diabetes were less likely to have DR at entry date compared with those with classical type 2 diabetes, whereas individuals with insulinopenic type 2 diabetes were more likely to have DR. In multivariable Cox regression analysis, individuals with hyperinsulinemic type 2 diabetes had a decreased risk of both incidence and progression of DR compared to those with classical type 2 diabetes. We did not find any clear difference in risk of incident or progression of DR in individuals with insulinopenic compared to classical type 2 diabetes. These findings indicate that subcategorization of type 2 diabetes is important in evaluating the risk of DR.

ARTICLE HIGHLIGHTS

Nonlinear relationship between body mass index and serum uric acid: An observational and Mendelian randomization study among Chinese adults

BACKGROUND AND AIMS

Conflicting evidence exists on the relationship between body mass index (BMI) and serum uric acid (SUA), and importantly, the causal role of BMI in SUA remains unclear. We aimed to evaluate the BMI-SUA relationship and its causality among Chinese adults using observational and Mendelian randomization (MR) analyses.

METHODS AND RESULTS

Study included 6641 adults from East China. A genetic risk score based on 14 BMI-associated East Asian variants was formulated. One-sample MR and non-linear MR analyses assessed the causal link between BMI_GRS and SUA levels. Mean BMI levels were 24.8 (SD 3.4) and 24.3 (SD 3.6) kg/m2 in men and women, respectively. Spline models revealed gender-specific BMI-SUA associations: a reverse J-shape for men and a J-shape for women (P-values for nonlinearity <0.05). In men, BMI showed a positive correlation with SUA levels when BMI was below 29.6 kg/m2 (beta coefficient 19.1 [95 % CI 15.1, 23.0] μmol/L per 1-SD increase in BMI), while in women, BMI exhibited a negative correlation with SUA levels when the BMI was less than 21.7 kg/m2 (beta coefficient -12.9 [95 % CI -21.6, -4.1] μmol/L) and a positive correlation when BMI exceeded 21.7 kg/m2 (beta coefficient 13.3 [95 % CI 10.9, 15.8] μmol/L). Furthermore, MR analysis suggested non-linear BMI-SUA link in women but not men.

CONCLUSION

Our study indicates a non-linear correlation between BMI and SUA in both genders. It is noteworthy that in women, this correlation may have a causal nature. Nevertheless, further longitudinal investigations are required to authenticate our findings.

The role of C-peptide in diabetes and its complications: an updated review

Worldwide, diabetes and its complications have seriously affected people's quality of life and become a serious public health problem. C-peptide is not only an indicator of pancreatic β-cell function, but also a biologically active peptide that can bind to cell membrane surface signaling molecules and activate downstream signaling pathways to play antioxidant, anti-apoptotic and inflammatory roles, or regulate cellular transcription through internalization. It is complex how C-peptide is related to diabetic complications. Both deficiencies and overproduction can lead to complications, but their mechanisms of action may be different. C-peptide replacement therapy has shown beneficial effects on diabetic complications in animal models when C-peptide is deficient, but results from clinical trials have been unsatisfactory. The complex pattern of the relationship between C-peptide and diabetic chronic complications has not yet been fully understood. Future basic and clinical studies of C-peptide replacement therapies will need to focus on baseline levels of C-peptide in addition to more attention also needs to be paid to post-treatment C-peptide levels to explore the optimal range of fasting C-peptide and postprandial C-peptide maintenance.

Development and evaluation of a risk prediction model for diabetes mellitus type 2 patients with vision-threatening diabetic retinopathy

OBJECTIVE

This study aims to develop and evaluate a non-imaging clinical data-based nomogram for predicting the risk of vision-threatening diabetic retinopathy (VTDR) in diabetes mellitus type 2 (T2DM) patients.

METHODS

Based on the baseline data of the Guangdong Shaoguan Diabetes Cohort Study conducted by the Zhongshan Ophthalmic Center (ZOC) in 2019, 2294 complete data of T2DM patients were randomly divided into a training set (n=1605) and a testing set (n=689). Independent risk factors were selected through univariate and multivariate logistic regression analysis on the training dataset, and a nomogram was constructed for predicting the risk of VTDR in T2DM patients. The model was evaluated using receiver operating characteristic (ROC) curves and area under the curve (AUC) in the training and testing datasets to assess discrimination, and Hosmer-Lemeshow test and calibration curves to assess calibration.

RESULTS

The results of the multivariate logistic regression analysis showed that Age (OR = 0.954, 95% CI: 0.940-0.969, p = 0.000), BMI (OR = 0.942, 95% CI: 0.902-0.984, p = 0.007), systolic blood pressure (SBP) (OR =1.014, 95% CI: 1.007-1.022, p = 0.000), diabetes duration (10-15y: OR =3.126, 95% CI: 2.087-4.682, p = 0.000; >15y: OR =3.750, 95% CI: 2.362-5.954, p = 0.000), and glycated hemoglobin (HbA1C) (OR = 1.325, 95% CI: 1.221-1.438, p = 0.000) were independent risk factors for T2DM patients with VTDR. A nomogram was constructed using these variables. The model discrimination results showed an AUC of 0.7193 for the training set and 0.6897 for the testing set. The Hosmer-Lemeshow test results showed a high consistency between the predicted and observed probabilities for both the training set (Chi-square=2.2029, P=0.9742) and the testing set (Chi-square=7.6628, P=0.4671).

CONCLUSION

The introduction of Age, BMI, SBP, Duration, and HbA1C as variables helps to stratify the risk of T2DM patients with VTDR.

Systemic C-peptide supplementation ameliorates retinal neurodegeneration by inhibiting VEGF-induced pathological events in diabetes

Diabetic retinopathy (DR) is caused by retinal vascular dysfunction and neurodegeneration. Intraocular delivery of C-peptide has been shown to be beneficial against hyperglycemia-induced microvascular leakage in the retina of diabetes; however, the effect of C-peptide on diabetes-induced retinal neurodegeneration remains unknown. Moreover, extraocular C-peptide replacement therapy against DR to avoid various adverse effects caused by intravitreal injections has not been studied. Here, we demonstrate that systemic C-peptide supplementation using osmotic pumps or biopolymer-conjugated C-peptide hydrogels ameliorates neurodegeneration by inhibiting vascular endothelial growth factor-induced pathological events, but not hyperglycemia-induced vascular endothelial growth factor expression, in the retinas of diabetic mice. C-peptide inhibited hyperglycemia-induced activation of macroglial and microglial cells, downregulation of glutamate aspartate transporter 1 expression, neuronal apoptosis, and histopathological changes by a mechanism involving reactive oxygen species generation in the retinas of diabetic mice, but transglutaminase 2, which is involved in retinal vascular leakage, is not associated with these pathological events. Overall, our findings suggest that systemic C-peptide supplementation alleviates hyperglycemia-induced retinal neurodegeneration by inhibiting a pathological mechanism, involving reactive oxygen species, but not transglutaminase 2, in diabetes.

A Nomogram for Predicting Vision-Threatening Diabetic Retinopathy Among Mild Diabetic Retinopathy Patients: A Case-Control and Prospective Study of Type 2 Diabetes

AIM

This study aims to develop a nomogram for predicting vision-threatening diabetic retinopathy (VTDR) in type 2 diabetes mellitus (T2DM) with mild non-proliferative diabetic retinopathy (NPDR) patients.

MATERIALS AND METHODS

In case-control analysis, 440 patients with mild NPDR or VTDR were enrolled to identify predictors and develop a nomogram. In the prospective cohort, 120 T2DM patients with mild NPDR were enrolled for external validation. Sensitivity, specificity, and area under the receiver operating characteristic (AUC) were calculated to evaluate the predictive performance of the nomogram.

RESULTS

In case-control analysis, 2-h C-peptide (OR = 0.85, 95% CI: 0.75 to 0.95, p = 0.006), sural nerve conduction impaired (SNCI) (mildly: OR = 2.18, 95% CI: 1.10 to 4.33, p = 0.026; moderately/severely: 3.66, 95% CI: 1.74 to 7.70, p < 0.001) and UACR (microalbuminuria: OR = 2.37, 95% CI: 1.25 to 4.48, p = 0.008; macroalbuminuria: 4.02, 95% CI: 1.61 to 10.06, p = 0.003) were identified as independent predictors. The concordance index of the prediction nomogram was 0.76 in the training set. In the test set, sensitivity, specificity, and AUC were 84.8%, 60.6%, and 0.73, respectively. In the prospective cohort, median follow-up period was 42 months, and 15 patients (12.5%) developed VTDR. Sensitivity, specificity, and AUC of prediction were 66.7%, 89.5%, and 0.75, respectively.

CONCLUSION

Introducing 2-h C-peptide, UACR, and SNCI, the nomogram demonstrated a good discriminatory power for predicting risk of VTDR in mild NPDR individuals.

Association of Obesity Indices with Diabetic Kidney Disease and Diabetic Retinopathy in Type 2 Diabetes: A Real-World Study

Background

Diabetic microvascular complications mainly include diabetic kidney disease (DKD) and diabetic retinopathy (DR). Obesity was recognized as a risk factor for DKD, while the reported relationship between obesity and DR was inconsistent. Moreover, whether the associations can be attributed to C-peptide levels is unknown.

Methods

Data from 1142 sequential inpatients with T2DM at Xiangyang Central Hospital between June 2019 and March 2022 were extracted retrospectively from the electronic medical record system. The associations between four obesity indices (body mass index (BMI), waist-hip circumference ratio (WHR), visceral fat tissue area (VFA), and subcutaneous fat tissue area (SFA)) and DKD and DR were evaluated. Whether the associations can be attributed to C-peptide levels was also explored.

Results

Obesity was a risk factor for DKD after adjusting for sex, HbA1c, TG, TC, HDL, LDL, smoking history, education, duration of diabetes, and insulin use (obesity indices: BMI (OR 1.050: 95% CI: 1.008-1.094; P = 0.020); WHR (OR 10.97; 95% CI: 1.250-92.267; P = 0.031); VFA (OR 1.005; 95% CI: 1.001-1.008; P = 0.008)), but it became insignificant after further adjusting for fasting C-peptide. The associations between BMI, WHR, VFA, and DKD might be U-shaped. Obesity and FCP tended to protect against DR; however, they became insignificant after adjusting for multiple potential confounders. C2/C0 (the ratio of the postprandial serum C-peptide to fasting C-peptide) was a protective factor for both DKD (OR 0.894, 95% CI: 0.833-0.959, P < 0.05) and DR (OR 0.851, 95% CI: 0.787-0.919; P < 0.05).

Conclusions

Obesity was a risk factor for DKD, and the effect may be attributable to C-peptide, which represents insulin resistance. The protective effect of obesity or C-peptide on DR was not independent and could be confounded by multiple factors. Higher C2/C0 was associated with both decreased DKD and DR.

Influence of inflammatory plasma biomarkers on choroidal thickness in type 2 diabetes mellitus

PURPOSE

To assess the influence of inflammatory plasma biomarkers on choroidal thickness (CT) in patients with type 2 diabetes (T2D).

METHODS

Cross-sectional study enrolling T2D patients and age-matched healthy controls (>55 years of age, Caucasian, axial length <26 mm, no macular edema, and naïve). Patients were examined with swept-source OCT Triton, obtaining automatic measurements. CT was analyzed using the ETDRS grid and the recently proposed choroidal division. A blood analysis was commanded: general biochemical profile, liver status, T2D status, thyroid and parathyroid activity, coagulation, general immunological profile, and inflammatory biomarkers.

RESULTS

124 eyes of 124 patients with a mean age between 66 and 68 years were examined. The new choroidal division showed differences between groups (p < 0.05) in more sectors than the ETDRS grid, and more biomarkers influenced these new sectors. T2D patients had higher levels of IL-8, TNF-α, MCP1, adiponectin and L-selectin. CT was influenced by TNF-α, IL-17, leukocytes and erythrocyte sedimentation rate, as well as by HDL cholesterol, albumin, liver function biomarkers, and TSH. HbA1c showed little influence on CT.

CONCLUSIONS

T2D patients present increased plasma inflammatory biomarkers, exhibiting an influence on CT. IL-17 is related to a thicker choroid but TNF-α is related to a thinner choroid. HbA1c has little influence on CT. The recently proposed choroidal division is more sensitive to CT changes than the ETDRS grid. Some sectors are more sensitive to plasma biomarkers.

Positive association of glucagon with bone turnover markers in type 2 diabetes: A cross-sectional study

AIMS

The osteo-metabolic changes in type 2 diabetes (T2D) patients are intricate and have not been fully revealed. It is not clear whether glucagon is entirely harmful in the pathogenesis of diabetes or a possible endocrine counter-regulation mechanism to reverse some abnormal bone metabolism. This study aimed to investigate the association between glucagon and bone turnover markers (BTMs) in T2D patients.

METHODS

A total of 3984 T2D participants were involved in a cross-sectional study in Shanghai, China. Serum glucagon was measured to elucidate its associations with intact N-terminal propeptide of type I collagen (P1NP), osteocalcin (OC), and β-C-terminal telopeptide (β-CTX). Glucagon was detected with a radioimmunoassay. Propeptide of type I collagen, OC, and β-CTX were detected using chemiluminescence. The diagnosis of T2D was based on American Diabetes Association criteria.

RESULTS

The concentration of glucagon was positively correlated with two BTMs [OC-β: 0.034, 95% CI: 0.004, 0.051, p = 0.024; CTX-β: 0.035, 95% CI: 0.004, 0.062, p = 0.024]. The result of P1NP was [P1NP-regression coefficient (β): 0.027, 95% CI: -0.003, 0.049, p = 0.083]. In the glucagon tertiles, P for trend of the BTMs is [P1NP: 0.031; OC: 0.038; CTX: 0.020], respectively.

CONCLUSIONS

Glucagon had a positive effect on bone metabolism. The concentrations of the three BTMs increased as glucagon concentrations rose. This implied that glucagon might speed up skeletal remodelling, accelerate osteogenesis, and promote the formation of mature bone tissue. At the same time, the osteoclastic process was also accelerated, providing raw materials for osteogenesis to preserve the dynamic balance. In view of the successful use of single-molecule as well as dual/triple agonists, it would be feasible to develop a preparation that would reduce osteoporosis in diabetic patients.

C-peptide, glycaemic control, and diabetic complications in type 2 diabetes mellitus: A real-world study

OBJECTIVE

To explore the relationship between C-peptide and glycaemic control rate and diabetic complications (microvascular complication and cerebral infarction) and provide evidence for stratified treatment of type 2 diabetes mellitus (T2DM)-based C-peptide.

METHOD

This is a cross-sectional real-world observational study. According to the inclusion and exclusion criteria, we studied 1377 patients with T2DM, grouped by fasting C-peptide and HOMA-IR. Blood samples were collected after fasting overnight. Logistic regression was used to analyse the relationship among fasting C-peptide, HOMA-IR, C2/C0 ratio (the ratio of 2 h postprandial C-peptide to fasting C-peptide), glycaemic control rate, and occurrence of diabetic complications. Restricted cubic spline (RCS) curves based on logistic regression were used to evaluate the relationship between C-peptide, glycaemic control rate, and diabetic kidney disease (DKD).

RESULTS

Patients were subdivided according to their fasting C-peptide in 4 groups (Q1,Q2,Q3,Q4). Patients of group Q3 (1.71 ≤ C-peptide < 2.51 ng/ml) showed the lowest incidence of DKD, diabetic retinopathy (DR), and rate of insulin absorption as welll as higher glycaemic control rate. Logistic regression shows that the probability of reaching glycemic control increased with higher levels of C-peptide, compared with group Q1, after adjusting for age, gender, duration of diabetes, body mass index, systolic blood pressure, diastolic blood pressure, creatinine, low-density lipoprotein, triglyceride, total cholesterol, and high-density lipoprotein. RCS curve shows that, when C-peptide is ≤2.68 ng/ml, the incidence of not reaching glycaemic control decreases with increasing C-peptide. The possibility of not reaching glycaemic control decreased with increasing C2/C0, when C-peptide is ≥1.71 ng/ml. RCS curve shows that the relationship between C-peptide and DKD follows a U-style curve. When C-peptide is <2.84 ng/ml, the incidence of DKD decreased with increasing C-peptide. With the increase in the C2/C0 ratio, the incidence of DKD, DR, and fatty liver did not decrease.

CONCLUSION

When C-peptide is ≥ 1.71 and < 2.51 ng/ml, patients with T2DM had a higher glycemic control rate. Excessive C-peptide plays different roles in DKD and DR; C-peptide may promote the incidence of DKD but protects patients from DR. Higher C2/C0 ratio is important for reaching glycaemic control but cannot reduce the risk of DKD, DR, and fatty liver.

FSH may mediate the association between HbA1c and bone turnover markers in postmenopausal women with type 2 diabetes

INTRODUCTION

Recent studies in postmenopausal women have found associations of follicle-stimulating hormone (FSH) levels with both glucose metabolism and bone turnover. The objective of the study was to investigate whether FSH may contribute to suppressed bone turnover markers (BTMs) in postmenopausal women with type 2 diabetes (T2D).

MATERIALS AND METHODS

888 postmenopausal women with T2D, 352 nondiabetes (prediabetes plus normoglycemia) were included from the METAL study. HbA1c, sex hormones, 25-hydroxy vitamin D (25(OH)D), serum procollagen type I N-terminal propeptide (P1NP), and β-C-terminal telopeptide (β-CTX) were measured.

RESULTS

P1NP and β-CTX decreased in postmenopausal T2D women compared with nondiabetes controls (both p < 0.001). The major factors responsible for the changes in P1NP were HbA1c (β = - 0.050, p < 0.001), 25(OH)D (β = - 0.003, p = 0.006), FSH (β = 0.001, p = 0.044) and metformin (β = - 0.109, p < 0.001), for β-CTX were HbA1c (β = - 0.049, p < 0.001), body mass index (BMI) (β = - 0.011, p = 0.005), 25(OH)D (β = - 0.003, p = 0.003), FSH (β = 0.002, p = 0.022) and metformin (β = - 0.091, p = 0.001) in postmenopausal T2D women based on multivariate regression analysis. With the increase in HbA1c, FSH decreased significantly (p for trend < 0.001). Mediation analysis demonstrated that FSH partly mediated the suppression of LnP1NP and Lnβ-CTX by HbA1c (β = - 0.009 and - 0.010, respectively), and Lnβ-CTX by BMI (β = - 0.015) when multiple confounders were considered (all p < 0.05).

CONCLUSION

HbA1c was the crucial determinant contributing to the suppression of BTMs. FSH might play a novel mediation role in BTM suppression due to HbA1c or BMI.

Application of urine C-peptide creatinine ratio in type 2 diabetic patients with different levels of renal function

OBJECTIVE

This study aims to investigate the effect of single urine C peptide/creatinine (UCPCR) in assessing the islet β Cell function of type 2 diabetes mellitus (T2DM) patients with different renal function.

METHODS

A total of 85 T2DM patients were recruited in this study, all the patients were assigned to one group with estimated glomerular filtration rate (eGFR)≤60 ml·min^-1·1.73 m^-2 and another group complicated with eGFR>60 ml·min^-1·1.73 m^-2. Serum creatinine, urine creatinine, serum fasting C-peptide (FCP), fasting blood glucose (FBG), glycosylated hemoglobin (HbA1C) and 24-hour urinary C-peptide (24hUCP) were measured. The modified homeostasis model assessment-islet β cell function [HOMA-islet (CP-DM)], the modified homeostasis model assessment-insulin resistance [HOMA-IR(CP)] and UCPCR were calculated.

RESULTS

When compared with group eGFR ≤60 ml·min^-1·1.73 m^-2, the levels of UCPCR, FCP, the modified HOMA-IR(CP) and HOMA-islet (CP-DM) were promoted and the concentrations of HbA1C, FPG, creatinine were decreased in the patients of eGFR>60 ml·min^-1·1.73 m^-2 (P<0.05); FCP was uncorrelated with 24hUCP while associated with UCPCR in the patients of eGFR ≤ 60 ml·min^-1·1.73 m^-2; UCPCR was positively correlated with FCP and HOMA-IR(CP) in the T2DM patients with different levels of renal function; the cut-off (UCPCR ≤ 1.13 nmol/g) had 88.37% sensitivity and 95.24% specificity [95% confidence interval (CI):0.919-0.997] for identifying severe insulin deficiency in T2DM patients[area under the curve (AUC) 0.978].

CONCLUSION

UCPCR can be used to evaluate islets β Cell function in T2DM patients with different renal function status.

Alterations of glycaemia, insulin resistance and body mass index within the C-peptide optimal range in non-diabetic patients

The study focused on changes or cut-offs of glycaemia, insulin resistance and body mass index within the C-peptide reference range (260-1730 pmol/l). The metabolic profile of individuals in the Czech Republic without diabetes (n = 3186) was classified by whiskers and quartiles of C-peptide into four groups with the following ranges: 290-510 (n = 694), 511-710 (n = 780), 711-950 (n = 720) and 951-1560 pmol/l (n = 673). Fasting levels of glucose, insulin, HOMA IR (Homeostasis Model Assessment for Insulin Resistance) and BMI (body mass index) were compared by a relevant C-peptide range. Participants taking medication to control glycaemia were excluded. The evaluation involved correlations between C-peptides and the above parameters, F-test and t-test. Changes in glucose levels (from 5.3 to 5.6 mmol/l) between the groups were lower in comparison to insulin, which reached relatively greater changes (from 4.0 to 14.2 mIU/l). HOMA IR increased considerably with growing C-peptide concentrations (0.9, 1.5, 2.2 and 3.5) and BMI values showed a similar trend (28.3, 31.0, 33.6 and 37.4). Considerable changes were observed for insulin (5.2 mIU/l, 57.8%) and HOMA IR (1.3, 61.3%) between groups with C-peptide ranges of 711-950 and 951-1560 pmol/l. Although correlations involving C-peptide, insulin, glucose and BMI seemed to be non-significant (up to rxy = 0.25), the mean values of insulin, HOMA IR and BMI showed statistically significant changes between all groups with various C-peptide concentrations (p ≤ 0.001). Generally, most important differences appeared in glucose metabolism and body mass index between C-peptide ranges of 711-950 and 951-1560 pmol/l. Absolute and relative changes of C-peptide concentrations are possible to use for the assessment of glucose regulatory mechanism. The spectrum of investigated parameters could be a useful tool to prevent the risks linked with the alterations of glycaemia.

A Pilot Proteomic Study of Normal Human Tears: Leptin as a Potential Biomarker of Metabolic Disorders

The concentrations of insulin, leptin, active ghrelin, C-peptide and gastric inhibitory polypeptide (GIP) and their inter-day variations were examined in normal human tears. In addition, correlations between the concentrations of these metabolic proteins and ocular surface parameters were determined. Subjects with healthy ocular surfaces attended three visits, with 7-day intervals. Tear evaporation rate (TER) and non-invasive tear break-up time (NITBUT) were assessed, and a total of 2 µL tears were collected from all subjects. Tear fluid concentrations of insulin, leptin, active ghrelin, C-peptide and GIP were measured by multiplex bead analysis. Insulin was the most highly expressed metabolic protein, followed by leptin, C-peptide, active ghrelin and GIP. Of these, only active ghrelin had a significant inter-day variation (p < 0.05). There was no inter-day variation in the mean concentrations of the other metabolic proteins. Leptin had a strong intra-class reproducibility. No correlation was detected between tear metabolic protein concentrations and ocular surface parameters. This pilot study shows, for the first time, that active ghrelin and GIP are detectable in healthy tears. The strong intra-class reproducibility for leptin shows that it could be used as a potential tear fluid biomarker and, possibly, in determining the effects of metabolic disorders on the ocular surface.

Association of Insulin Resistance and β-cell Function With Bone Turnover Biomarkers in Dysglycemia Patients

Background

The interrelation between glucose and bone metabolism is complex and has not been fully revealed. This study aimed to investigate the association between insulin resistance, β-cell function and bone turnover biomarker levels among participants with abnormal glycometabolism.

Methods

A total of 5277 subjects were involved through a cross-sectional study (METAL study, http://www.chictr.org.cn, ChiCTR1800017573) in Shanghai, China. Homeostasis model assessment of insulin resistance (HOMA-IR) and β-cell dysfunction (HOMA-%β) were applied to elucidate the nexus between β-C-terminal telopeptide (β-CTX), intact N-terminal propeptide of type I collagen (P1NP) and osteocalcin (OC). β-CTX, OC and P1NP were detected by chemiluminescence.

Results

HOMA-IR was negatively associated with β-CTX, P1NP and OC (regression coefficient (β) -0.044 (-0.053, -0.035), Q4vsQ1; β -7.340 (-9.130, -5.550), Q4vsQ1 and β -2.885 (-3.357, -2.412), Q4vsQ1, respectively, all P for trend <0.001). HOMA-%β was positively associated with β-CTX, P1NP and OC (β 0.022 (0.014, 0.031), Q4vsQ1; β 6.951 (5.300, 8.602), Q4vsQ1 and β 1.361 (0.921, 1.800), Q4vsQ1, respectively, all P for trend <0.001).

Conclusions

Our results support that lower bone turnover biomarker (β-CTX, P1NP and OC) levels were associated with a combination of higher prevalence of insulin resistance and worse β-cell function among dysglycemia patients. It is feasible to detect bone turnover in diabetes or hyperglycemia patients to predict the risk of osteoporosis and fracture, relieve patients' pain and reduce the expenses of long-term cure.

The unique association between the level of peripheral blood monocytes and the prevalence of diabetic retinopathy: a cross-sectional study

OBJECTIVE

The attraction and influx of monocytes into the retina has been considered a critical step in the development of diabetic retinopathy (DR). However, large population studies about the association between peripheral blood monocyte levels, an inexpensive and easily measurable laboratory index, and DR are limited. Thus, we aimed to investigate the association between peripheral blood monocyte levels and DR.

METHODS

A total of 3223 participants out of 3277 adults with diabetes were enrolled from seven communities in China in this cross-sectional survey. Participants underwent several medical examinations, including the measurement of anthropometric factors, blood pressure, routinely analyzed leukocyte characteristics, glucose, lipid profiles, urine albumin/creatinine ratio and fundus photographs.

RESULTS

The prevalence of DR among the participants in the highest quartile of peripheral blood monocyte levels significantly decreased by 41% (OR 0.59; 95% CI 0.43, 0.81) compared with the participants in the first quartile (P for trend < 0.05). However, there were no associations between the monocyte level and the prevalence of cardiovascular and cerebrovascular diseases (CVD) and diabetic kidney disease (DKD) (both P for trend > 0.05). Associations between leukocyte, neutrophil and lymphocyte levels and DR were also not found (all P for trend > 0.05). These associations were all fully adjusted for age, sex, education status, duration of diabetes history, current smoking, BMI, HbA1c, dyslipidemia, systolic blood pressure and insulin therapy.

CONCLUSION

Decreased peripheral blood monocyte levels were associated with increased odds of DR after adjusting for potential confounders in diabetic adults. However, causation remains to be demonstrated.

Fasting C-peptide, a biomarker for hypoglycaemia risk in insulin-naïve people with type 2 diabetes initiating basal insulin glargine 100 U/mL

AIM

To examine the relationship between baseline fasting C-peptide (FCP) and outcomes in insulin-naïve people with type 2 diabetes initiating basal insulin glargine 100 U/mL (Gla-100).

MATERIALS AND METHODS

Post hoc pooled analysis of nine randomized, treat-to-target trials in patients with type 2 diabetes inadequately controlled on oral antihyperglycaemic drugs initiating once-daily Gla-100. Participants (n = 2165) were stratified at baseline according to FCP (≤0.40, >0.40-1.20, >1.20-2.00, >2.00 nmol/L). Glycaemic control, body weight, insulin dose and hypoglycaemia were determined at 24 weeks.

RESULTS

At baseline low FCP levels were associated with longer known diabetes duration, lower body mass index and higher fasting plasma glucose (FPG). Following Gla-100 introduction, the mean HbA1c reduction at week 24 was similar in all four FCP groups, albeit fewer people in the lowest FCP group achieved HbA1c <7.0% versus FCP groups >0.40 nmol/L. By contrast, FPG reduction and proportion reaching FPG ≤5.6 mmol/L were greatest in the lowest FCP group, diminishing at higher FCP levels. Gla-100 dose at week 24 was lowest in the ≤0.40 nmol/L FCP group and highest in the >1.20 nmol/L FCP group. Incidence and event rate of overall, nocturnal and severe hypoglycaemia were higher at week 24 in groups with lower FCP levels. In multivariable regression analysis baseline FCP, concomitant sulphonylurea use and endpoint HbA1c were strong predictors of hypoglycaemia.

CONCLUSIONS

FCP levels identified patients with type 2 diabetes experiencing different responses to basal insulin Gla-100. A low FCP identifies a markedly insulin-deficient, insulin-sensitive subgroup/phenotype with an enhanced risk of hypoglycaemia, which requires a low initial basal insulin dose, cautious titration and earlier addition of prandial glucose-lowering therapy.

Associations between the Neutrophil-to-Lymphocyte Ratio and Diabetic Complications in Adults with Diabetes: A Cross-Sectional Study

OBJECTIVE

The neutrophil-to-lymphocyte ratio (NLR) is an inexpensive and easily measurable laboratory index indicating systemic inflammation, while the application of many other inflammatory markers has been limited in daily clinical practice. However, large population studies about investigating the associations of the NLR level with diabetic complications including cardiovascular and cerebrovascular diseases (CVD), diabetic kidney disease (DKD), and diabetic retinopathy (DR) in the same population were limited. The aim of our study is to evaluate the associations between the NLR level and the prevalence of CVD, DKD, and DR in adults with diabetes simultaneously.

METHODS

A cross-sectional survey of 4,813 diabetic adults was conducted in seven communities in China. Persons underwent several medical examinations, including the measurement of anthropometric factors, blood pressure, routinely analyzed leukocyte characteristics, glucose, lipid profiles, urine albumin/creatinine ratio, and fundus photographs.

RESULTS

Compared with the first quartile of the NLR level, the odds of having CVD was significantly increased by 21% for participants in the highest quartile (OR 1.21; 95% CI 1.00, 1.47) (P for trend < 0.05). Similarly, the prevalence of DKD among participants in the highest quartile of the NLR level was significantly increased by 150% (OR 2.50; 95% CI 1.95, 3.19) (P for trend < 0.05). However, no association was found between the NLR level and the prevalence of DR (P for trend > 0.05). These associations were all fully adjusted.

CONCLUSIONS

A higher NLR level was associated with an increased prevalence of CVD and DKD, other than DR, in diabetic adults.

The Associations Between Gonadal Hormones and Serum Uric Acid Levels in Men and Postmenopausal Women With Diabetes

Introduction: In assessing the development of hyperuricemia in diabetic adults, the role of the sex steroid axis is underappreciated. Furthermore, dehydroepiandrosterone (DHEA) has been recommended as a nutritional supplement. However, is DHEA suitable for diabetic adults with hyperuricemia? This issue has received little attention. Aim: The objective of this study was to investigate the associations between gonadal hormones and uric acid (UA) levels in diabetic adults, paying particular attention to the association between DHEA and UA levels. Methods: We analyzed 4,426 participants out of 4,813 diabetic adults enrolled from seven communities in a cross-sectional survey conducted in 2018. Participants underwent several examinations, including assessments of anthropometric parameters, blood pressure, glucose, lipid profiles, UA, total testosterone (TT), estradiol (E2), the follicle-stimulating hormone (FSH), the luteinizing hormone (LH), and dehydroepiandrosterone (DHEA). Results: Among men and compared with individuals in the first quartile, participants in the fourth quartile of TT and FSH had odds of hyperuricemia that were significantly decreased by so much as 48 and 34%, respectively (both P < 0.05). However, participants in the fourth quartile of DHEA had 79% increased odds of hyperuricemia (P < 0.05). Among postmenopausal women, participants in the fourth quartile of DHEA, TT, and LH had odds of hyperuricemia that were significantly increased by 155, 99, and 76%, respectively (all P < 0.05). These associations were adjusted for potential confounding factors. Conclusions: Sex differences were found in the associations between gonadal hormones and UA levels in diabetic men and postmenopausal women, which should be monitored to prevent hyperuricemia when sex hormone treatment, especially DHEA, is administered. Further studies are needed.

Bone Turnover Markers and Probable Advanced Nonalcoholic Fatty Liver Disease in Middle-Aged and Elderly Men and Postmenopausal Women With Type 2 Diabetes

Objective: Type 2 diabetic patients have a higher incidence of nonalcoholic steatohepatitis (NASH) and advanced stages of fibrosis, and nonalcoholic fatty liver disease (NAFLD) is associated with impaired bone health. We aimed to investigate whether bone turnover is associated with the probable presence of NASH and fibrosis. Methods: In total, 4,937 diabetic participants from Shanghai, China were enrolled in 2018. Subjects with NAFLD were categorized into simple NAFLD and probable NASH groups based on the presence of a metabolic syndrome. The NAFLD fibrosis score was used to identify patients with a higher likelihood of advanced fibrosis. Results: In postmenopausal women, large N-mid fragment of osteocalcin (N-MID osteocalcin) was negatively associated with probable NASH (P for trend < 0.001). β-C-terminal cross-linked telopeptides of type I collagen (β-CTX) and procollagen type I N-terminal propeptide (P1NP) were positively associated with the probable presence of significant fibrosis in postmenopausal women (P for trend 0.015 and <0.001). However, in men, N-MID osteocalcin and β-CTX were negatively associated with the probable presence of significant fibrosis (P for trend 0.029 and 0.027). Conclusions: Significant associations among N-MID osteocalcin, β-CTX and P1NP, and probable advanced NAFLD were observed. Further prospective and animal studies are warranted to understand the causal relationship and underlying mechanism.