Multiple Cell Signalling Pathways of Human Proinsulin C-Peptide in Vasculopathy Protection

Impact of Fat Distribution and Metabolic Diseases on Cerebral Microcirculation: A Multimodal Study on Type 2 Diabetic and Obese Patients

Background: Since metabolic diseases and atherosclerotic vascular events are firmly associated, herein we investigate changes in central microcirculation and atherosclerosis-related body fat distribution in patients with type 2 diabetes mellitus and obesity. Methods: Resting brain perfusion single-photon emission computed tomography (SPECT) imaging with Technetium-99m hexamethylpropylene amine oxime ([99mTc]Tc-HMPAO SPECT) was performed, and the breath-holding index (BHI) and carotid intima-media thickness (cIMT) were measured to characterise central microcirculation. Besides CT-based abdominal fat tissue segmentation, C-peptide level, glycaemic and anthropometric parameters were registered to search for correlations with cerebral blood flow and vasoreactivity. Results: Although no significant difference was found between the resting cerebral perfusion of the two patient cohorts, a greater blood flow increase was experienced in the obese after the breath-holding test than in the diabetics (p < 0.05). A significant positive correlation was encountered between resting and provocation-triggered brain perfusion and C-peptide levels (p < 0.005). BMI and cIMT were negatively correlated (rho = -0.27 and -0.23 for maximum and mean cIMT, respectively), while BMI and BHI showed a positive association (rho = 0.31 and rho = 0.29 for maximum and mean BHI, respectively), which could be explained by BMI-dependent changes in fat tissue distribution. cIMT demonstrated a disproportional relationship with increasing age, and higher cIMT values were observed for the men. Conclusions: Overall, C-peptide levels and circulatory parameters seem to be strong applicants to predict brain microvascular alterations and related cognitive decline in such patient populations.

Decreased glucagon in diabetic peripheral neuropathy patients with long duration type 2 diabetes

OBJECTIVE

The aim of this study was to investigate the association of fasting C-peptide and glucagon with diabetic peripheral neuropathy (DPN) in patients with type 2 diabetes (T2DM).

METHODS

A comprehensive evaluation was conducted on 797 patients with T2DM to assess the various risk factors affecting DPN. The subjects were categorized into short duration and long duration group according to the duration of diabetes with a threshold of 10 years. Logistic regression analysis was employed to examine the association between DPN and islet function, as well as other parameters. Receiver operating characteristic curve analysis was performed to evaluate the predictive capability of glucagon.

RESULTS

The fasting C-peptide levels were significantly lower in the DPN patients with short duration of diabetes, but lost significance in the long duration group. Conversely, a decreased level of glucagon was only observed in DPN patients with long duration of diabetes. For the group with long duration of diabetes, glucagon was the sole risk factor associated with DPN. The receiver operating characteristic curve analysis revealed that glucagon in the long duration group exhibited a moderate area under the curve of 0.706.

CONCLUSIONS

The serum glucagon levels in T2DM patients with DPN exhibited bidirectional changes based on the duration of diabetes. Decreased glucagon was associated with DPN in T2DM patients with long duration of diabetes.

Neural Stem Cell-based Regenerative Therapy: A New Approach to Diabetes Treatment

Diabetes mellitus (DM) is the most common metabolic disorder that occurs due to the loss, or impaired function of insulin-secreting pancreatic beta cells, which are of two types - type 1 (T1D) and type 2 (T2D). To cure DM, the replacement of the destroyed pancreatic beta cells of islet of Langerhans is the most widely practiced treatment. For this, isolating neuronal stem cells and cultivating them as a source of renewable beta cells is a significant breakthrough in medicine. The functions, growth, and gene expression of insulin-producing pancreatic beta cells and neurons are very similar in many ways. A diabetic patient's neural stem cells (obtained from the hippocampus and olfactory bulb) can be used as a replacement source of beta cells for regenerative therapy to treat diabetes. The same protocol used to create functional neurons from progenitor cells can be used to create beta cells. Recent research suggests that replacing lost pancreatic beta cells with autologous transplantation of insulin-producing neural progenitor cells may be a perfect therapeutic strategy for diabetes, allowing for a safe and normal restoration of function and a reduction in potential risks and a long-term cure.

The HbA1c/C-Peptide Ratio is Associated With the No-Reflow Phenomenon in Patients With ST-Elevation Myocardial Infarction

Currently, the gold standard treatment for ST-elevation myocardial infarction (STEMI) is primary percutaneous coronary intervention (pPCI), but even after successful pPCI, a perfusion disorder in the epicardial coronary arteries, termed no-reflow phenomenon (NR), can develop, resulting in short- and long-term adverse events. The present study assessed the relationship between NR and HbA1c/C-peptide ratio (HCR) in 1834 consecutive patients who underwent pPCI due to STEMI. Participants were divided into two groups according to NR status and the demographic, clinical and periprocedural characteristics of the groups were compared. NR developed in 352 (19.1%) of the patients in the study. While C-peptide levels were significantly lower in the NR group, HbA1c and HCR were significantly higher (P < .001, for all). In multivariable analysis, C-peptide, HbA1c, and HCR, were determined as independent predictors for NR (P < .05, for all). In Receiver Operating Characteristic (ROC) analysis, HCR predicted the NR with 80% specificity and 77% sensitivity. In STEMI patients, combining HbA1c and C-peptide in a single fraction has a predictive value for NR independent of diabetes. This ratio may contribute to risk stratification of STEMI patients.

Comparison of customized vacuum sealing drainage and vacuum sealing drainage in the treatment of diabetic foot ulcers: a retrospective analysis

BACKGROUND

The prevalence of diabetic foot ulcers, a common, more serious chronic diabetes-related complication, is increasing. Vacuum sealing drainage (VSD) constitutes an effective adjunctive treatment for diabetic foot ulcers. Factors, such as poor glycemic control, ischemia, and infection prolong wound healing time, and VSD products are expensive and unaffordable for many patients.

OBJECTIVE

To compare the use of customized VSD and customized VSD in the treatment of diabetic foot ulcer.

METHOD

This retrospective study included 83 patients with diabetic foot ulcers in customized VSD (n = 44) and VSD (n = 39) groups. Baseline data, efficacy after 14 days, total treatment efficiency, final outcome (28 days after treatment, healing rate), average treatment cost, and hospitalization (days) of the two groups were compared. Factors affecting wound healing were analyzed.

RESULTS

No significant intergroup differences in the baseline data were detected (VSD vs. customized VAD, p > 0.05). Treatment efficacy was higher in the customized VSD group than in the VSD group after 14 days (p < 0.05), although total treatment efficiency in both groups reached 100%. The final outcome in the customized VSD group was better (vs. VSD group, p < 0.05), and the wound healing rate was higher than in the VSD group (66.7% vs. 33.3%). The mean treatment cost and hospital days were greater in the VSD group (vs. customized VSD group; p < 0.05). Factors affecting wound healing include age, Wagner classification, HDL-C, and fasting C-peptide. Younger age, low Wagner classification grade, low HDL-C level, and high fasting C-peptide contribute to higher healing rate, CONCLUSION: Efficacy and final outcome of customized VSD were better than that of VSD; the customized VSD device is simple and convenient to operate, and enables cost-effective treatment.

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.

Molecular Mechanisms for the Vicious Cycle between Insulin Resistance and the Inflammatory Response in Obesity

The comprehensive anabolic effects of insulin throughout the body, in addition to the control of glycemia, include ensuring lipid homeostasis and anti-inflammatory modulation, especially in adipose tissue (AT). The prevalence of obesity, defined as a body mass index (BMI) ≥ 30 kg/m², has been increasing worldwide on a pandemic scale with accompanying syndemic health problems, including glucose intolerance, insulin resistance (IR), and diabetes. Impaired tissue sensitivity to insulin or IR paradoxically leads to diseases with an inflammatory component despite hyperinsulinemia. Therefore, an excess of visceral AT in obesity initiates chronic low-grade inflammatory conditions that interfere with insulin signaling via insulin receptors (INSRs). Moreover, in response to IR, hyperglycemia itself stimulates a primarily defensive inflammatory response associated with the subsequent release of numerous inflammatory cytokines and a real threat of organ function deterioration. In this review, all components of this vicious cycle are characterized with particular emphasis on the interplay between insulin signaling and both the innate and adaptive immune responses related to obesity. Increased visceral AT accumulation in obesity should be considered the main environmental factor responsible for the disruption in the epigenetic regulatory mechanisms in the immune system, resulting in autoimmunity and inflammation.

Hot Spots for the Use of Intranasal Insulin: Cerebral Ischemia, Brain Injury, Diabetes Mellitus, Endocrine Disorders and Postoperative Delirium

A decrease in the activity of the insulin signaling system of the brain, due to both central insulin resistance and insulin deficiency, leads to neurodegeneration and impaired regulation of appetite, metabolism, endocrine functions. This is due to the neuroprotective properties of brain insulin and its leading role in maintaining glucose homeostasis in the brain, as well as in the regulation of the brain signaling network responsible for the functioning of the nervous, endocrine, and other systems. One of the approaches to restore the activity of the insulin system of the brain is the use of intranasally administered insulin (INI). Currently, INI is being considered as a promising drug to treat Alzheimer's disease and mild cognitive impairment. The clinical application of INI is being developed for the treatment of other neurodegenerative diseases and improve cognitive abilities in stress, overwork, and depression. At the same time, much attention has recently been paid to the prospects of using INI for the treatment of cerebral ischemia, traumatic brain injuries, and postoperative delirium (after anesthesia), as well as diabetes mellitus and its complications, including dysfunctions in the gonadal and thyroid axes. This review is devoted to the prospects and current trends in the use of INI for the treatment of these diseases, which, although differing in etiology and pathogenesis, are characterized by impaired insulin signaling in the brain.

Correlation between Glucose/C-Peptide Ratio and the Risk of Disease Progression in Diabetic Nephropathy Patients: A Clinical Retrospective Analysis

The aim of this study is to analyze the correlation between the glucose/C-peptide ratio and the risk of disease progression in patients with diabetic nephropathy. Ninety-three patients with diabetic nephropathy, who were treated in the Chun'an Branch of Zhejiang Provincial People's Hospital, China, from January 2016 to January 2019, were recruited as subjects. In accordance with the disease progression, the patients were divided into a progression group (n = 59) and a nonprogression group (n = 34). Clinical data were compared between the two groups. Pearson's correlation was applied to analyze the correlation of age, postprandial glucose/C-peptide, glycosylated hemoglobin, insulin resistance index, serum cystatin C, uric acid, 24 h urinary albumin excretion rate (24 hUAER), and estimated glomerular filtration rate (eGFR). Univariate and multivariate logistic regression models were utilized to analyze the influencing factors for the risk of disease progression in patients with diabetic nephropathy. The receiver operating characteristic (ROC) curve was employed to assess the predictive value of postprandial glucose/C-peptide on the risk of disease progression in patients with diabetic nephropathy. Results. The age differences, postprandial glucose/C-peptide, glycosylated hemoglobin, insulin resistance index, serum cystatin C, uric acid, 24 hUAER, and eGFR were significantly different between the two groups (P < 0.05). Pearson's linear correlation analysis exhibited that postprandial glucose/C-peptide, insulin resistance index, serum cystatin C, and uric acid were positively correlated with 24 hUAER (r = 0.514, 0.345, 0.311, 0.279, P < 0.05). Age, postprandial glucose/C-peptide, insulin resistance index, serum cystatin C, and uric acid were negatively correlated with eGFR (r = -0.210, -0.610, -0.351, -0.347, and -0.274, P < 0.05). Univariate logistic regression analysis displayed that age (OR = 0.938; P=0.043), postprandial glucose/C-peptide (OR = 0.851; p ≤ 0.001), insulin resistance index (OR = 0.219; p ≤ 0.001), serum cystatin C (OR = 0.113; p ≤ 0.001), and uric acid (OR = 0.989; P=0.001) were risk factors for the risk of disease progression in patients with diabetic nephropathy. Multivariate logistic regression analysis exhibited that postprandial glucose/C-peptide (OR = 0.747; P=0.004), insulin resistance index (OR = 0.072; P=0.012), serum cystatin C (OR = 0.023; P=0.020), and uric acid (OR = 0.967; P=0.039) were independent risk factors for the risk of disease progression in patients with diabetic nephropathy. The ROC curve results demonstrated that the AUC of postprandial glucose/C-peptide predicting the risk of disease progression in patients with diabetic nephropathy was 0.931. Postprandial glucose/C-peptide, insulin resistance index, serum cystatin C, and uric acid are correlated with 24hUAER and eGFR. Postprandial glucose/C-peptide, insulin resistance index, serum cystatin C, and uric acid are independent risk factors for the risk of disease progression in patients with diabetic nephropathy. Among them, postprandial glucose/C-peptide can be employed as a crucial indicator to predict the risk of disease progression in diabetic nephropathy patients.

Recent Progress of Research Regarding the Applications of Stem Cells for Treating Diabetes Mellitus

At present, the number of diabetes patients has exceeded 537 million worldwide and this number continues to increase. Stem cell therapy represents a new direction for the treatment of diabetes; the use of stem cells overcomes some shortcomings associated with traditional therapies. Functional β-cells play an important role in the pathogenesis of diabetes. As therapeutic targets, functional β-cells are restored by a variety of stem cells, including pluripotent stem cells, mesenchymal cells, and urine-derived stem cells. Although all types of stem cells have their own characteristics, they mainly promote the repair and regeneration of β-cells through directional differentiation, immunomodulation, and paracrine signaling after homing to the injured site. However, stem cell therapy still faces many obstacles, such as low long-term cell survival rate after transplantation, low maintenance time of blood glucose homeostasis, immune rejection, and tumorigenesis. Recently, genetically edited pluripotent stem cells and the co-transplantation of mesenchymal stem cells and islet cells have made significant progress in improving the efficacy of stem cell transplantation processes, also providing powerful tools for the study of the mechanisms underlying diabetes and disease modeling. In this review, we first focused on: (1) stem cells as a pool for the differentiation of insulin-producing cells; (2) stem cells as a source for regenerative repair of damaged islets and as a potential co-transplanted population with islets; (3) the potential of combining gene editing with stem cell therapy; and (4) selection of the stem cell transplantation approach. Based on these topics, we discuss the challenges within the field of adapting stem cell-supported and stem cell-derived transplantations, and the promising routes for overcoming these problems.

Plants and Diabetes: Description, Role, Comprehension and Exploitation

Many plants have been known for centuries to have medicinal importance with potential beneficial effects on health. Phytotherapeutic compounds are well known to play a globally significant role, in particular in the management and treatment of various chronic diseases. Among these, diabetes can cause long term damage to the body other than having a relevant economic burden on society being among the costliest chronic diseases. This motivated the focus of the proposed Special Issue, intended to develop and exploit the potential role of plants in the management and treatment of diabetes. The main topics included are: (i) description and use of medicinal plants for diabetes management; (ii) the elucidation and delineation of their main components, properties (anti-hyperglycaemic, hypoglicaemic, anti-infiammatory, apoptotic agents, etc.), (iii) the mechanism of action (in vitro and in vivo studies); (iv) formulation of nutraceuticals, botanicals, and dietary supplements useful as tools as an alternative or support to anti-diabetic pharmacological therapies; (v) development of new markers.

Association Between Serum Insulin and C-Peptide Levels and Breast Cancer: An Updated Systematic Review and Meta-Analysis

Background

Several studies have reported that hyperinsulinemia plays a part in the etiology of breast cancer. However, no consensus has been reached. Therefore, we conducted a meta-analysis to explore the role of insulin and C-peptide in breast cancer.

Methods

A systematic search in PubMed, Embase, and The Cochrane Library was conducted up to September, 2020. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were used to measure effect sizes. Publication bias was assessed using the Egger test. Stability of these results was evaluated using sensitivity analyses.

Results

Fourteen articles including 27,084 cases and five articles including 2,513 cases were extracted for serum insulin levels and C-peptide levels. We found that C-peptide levels were positively associated with breast cancer with overall SMD = 0.37 (95% CI = 0.09–0.65, I² = 89.1%). Subgroup analysis by control source illustrated a positive relationship between breast cancer and C-peptide levels in population-based control. Subgroup analysis by C-peptide level indicated a positive correlation between breast cancer and C-peptide levels no matter C-peptide levels in case group is ≤3 ng/ml or >3 ng/ml. Subgroup analysis by age showed that C-peptide level positively correlated to breast cancer in women between the ages of 50 and 60. However, we did not identify any relationship between breast cancer and insulin levels (SMD = 0.22, 95% CI = −0.06–0.50, I² = 97.3%).

Conclusion

This meta-analysis demonstrated that C-peptide levels were positively related to breast cancer in women, and no relationship between insulin levels and breast cancer was found.