c-peptide and Vascular-Diseases

A major hallmark of diabetes is a constant high blood glucose level (hyperglycaemia), resulting in endothelial dysfunction. Transient or prolonged hyperglycemia can cause diabetic vasculopathy, a secondary systemic damage. C-Peptide is a product of cleavage of proinsulin by a serine protease that occurs within the pancreatic β-cells, being secreted in similar amounts as insulin. The biological activity of human C-peptide is instrumental in the prevention of diabetic neuropathy, nephropathy and other vascular complications. The main feature of type 1 diabetes mellitus is the lack of insulin and of C-peptide, but the progressive β-cell loss is also observed in later stage of type 2 diabetes mellitus. C-peptide has multifaceted effects in animals and diabetic patients due to the activation of multiple cell signalling pathways, highlighting p38 mitogen-activated protein kinase and extracellular signal-regulated kinase ½, Akt, as well as endothelial nitric oxide production. Recent works highlight the role of C-peptide in the prevention and amelioration of diabetes and also in organ-specific complications. Benefits of C-peptide in microangiopathy and vasculopathy have been shown through conservation of vascular function, and also in the prevention of endothelial cell death, microvascular permeability, neointima formation, and in vascular inflammation. Improvement of microvascular blood flow by replacing a physiological amount of C-peptide, in several tissues of diabetic animals and humans, mainly in nerve tissue, myocardium, skeletal muscle, and kidney has been described. A review of the multiple cell signalling pathways of human proinsulin C-peptide in vasculopathy protection is proposed, where the approaches to move beyond the state of the art in the development of innovative and effective therapeutic options of diabetic neuropathy and nephropathy are discussed.

Topics: C-Peptide; Humans; MAP Kinase Signaling System; Nitric Oxide; Vascular Diseases

Current knowledge suggests a complex role of C-peptide in human physiology, but its mechanism of action is only partially understood. The effects of C-peptide appear to be variable depending on the target tissue, physiological environment, its combination with other bioactive molecules such as insulin, or depending on its concentration. It is apparent that C-peptide has therapeutic potential for the treatment of vascular and nervous damage caused by type 1 or late type 2 diabetes mellitus. The question remains whether the effect is mediated by the receptor, the existence of which is still uncertain, or whether an alternative non-receptor-mediated mechanism is responsible. The Institute of Endocrinology in Prague has been paying much attention to the issue of C-peptide and its metabolic effect since the 1980s. The RIA methodology of human C-peptide determination was introduced here and transferred to commercial production. By long-term monitoring of C-peptide oGTT-derived indices, the Institute has contributed to elucidating the pathophysiology of glucose tolerance disorders. This review summarizes the current knowledge of C-peptide physiology and highlights the contributions of the Institute of Endocrinology to this issue.

Topics: Animals; C-Peptide; Diabetes Mellitus, Type 2; Humans; Insulin Resistance; Nervous System Diseases; Vascular Diseases

This study investigates the connection between abnormal liver enzymes and macro vascular disease in type 2 diabetes mellitus (T2DM) patients with non-alcoholic fatty liver disease (NAFLD). Clinical data from 276 T2DM patients with NAFLD were retrospectively examined and divided into two groups based on the presence or absence of macro vascular disease. Various biochemical markers were tested, including fasting C-peptide, total bilirubin (TBil), total protein (TP), albumin (Alb), C-reactive protein (CRP) and the insulin resistance index (HOMA-IR). The study found no significant differences in demographic variables between the two groups. However, patients with macro vascular disease had significantly higher levels of fasting C-peptide, CRP, HOMA-IR, TBil, TP, Alb and certain blood lipid markers. The study concludes that in T2DM patients with NAFLD, increased blood lipids, liver function and inflammatory factors are risk factors for macro vascular disease, suggesting the importance of clinical management to lower macro vascular disease prevalence.

Topics: Albumins; Bilirubin; C-Peptide; C-Reactive Protein; Diabetes Mellitus, Type 2; Humans; Non-alcoholic Fatty Liver Disease; Retrospective Studies; Risk Factors; Vascular Diseases

Uremic type 2 diabetic patients on hemodialysis need various types of antidiabetic therapies. The aim of the present study was to identify differences between patients on oral antidiabetic drug therapy or insulin substitution or diet therapy alone during their first year of hemodialysis.. Sixty-four type 2 diabetic patients who had started hemodialysis (HD) at our dialysis center between 2003 and 2007 were included in the study. Kidney-transplanted patients (n = 1) and those with chronic infectious or malignant diseases (n = 4) were excluded. Patients were divided into three groups according to their antidiabetic therapy: group 1 consisted of patients on oral antidiabetic drug therapy (n = 12), group 2 of those on insulin therapy (n = 42), and group 3 of those being treated with diet alone (n = 10). At the start of HD and 12 months later, we measured fasting plasma glucose (FPG), HbA1c, the incidence of hypoglycemia (n/patient/month), cholesterol, triglycerides, body weight, and insulin requirements in the insulin-treated group. C-peptide was only measured at the start of dialysis. We evaluated changes in antidiabetic therapy during the first year on dialysis, and the prevalence of vascular disease in each group at the start of HD.. FPG and HbA1c values were similar in all groups at the start of HD and after 1 year. Hypoglycemia occurred more frequently in insulin-treated patients; however, the difference was not significant. Cholesterol levels were similar in all groups, whereas triglycerides were significantly lower in insulin-treated patients (138 ± 28 vs. 176 ± 46 mg/dl; P < 0.05). Body weight was similar in all groups. No significant change in body weight was observed in any group after 12 months on dialysis. At the start of HD, C-peptide levels were lower in insulin-treated patients than in the other groups (1.8 ± 0.9 ng/ml vs. 2.2 ± 1.1 and 2.4 ± 1.1 ng/ml; P < 0.05). During the first 12 months on HD, two patients from group 1 were shifted to group 3 (diet alone), while four patients could reduce their drug dosage (33%). However, two subjects became insulin-dependent. In group 2, insulin therapy could be terminated in two cases, while the insulin dose could be reduced in 20 patients (48%). In group 3, one patient was switched to oral antidiabetic therapy. The prevalence of vascular disease was slightly higher in group 3 (NS).. Within 1 year after the start of HD, the dose of sulfonylurea as well as insulin could be reduced in a large majority of patients. Metabolic control was similar in all groups. Only triglycerides were significantly lower in group 2. The frequency of hypoglycemia and the prevalence of vascular disease were just slightly higher in the group on insulin therapy.

Topics: Aged; Blood Glucose; Body Weight; C-Peptide; Cholesterol; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Glycated Hemoglobin; Humans; Hypoglycemia; Hypoglycemic Agents; Insulin; Kidney Failure, Chronic; Male; Middle Aged; Renal Dialysis; Sulfonylurea Compounds; Triglycerides; Vascular Diseases

Prevalence of metabolic syndrome (MetS) in type 2 diabetes and its association with vascular complications were studied in 637 Japanese type 2 diabetic patients. MetS was diagnosed using criteria proposed by the Japanese study group for the definition of MetS in 2005. The prevalence of MetS in patients studied was higher in males (45.9%) than females (28.0%). The prevalence of MetS was 53.0% in males and 35.4% in females in patients with duration of less than 10 years, and decreased with an increase in duration. Upon comparing patients groups complicated with and without MetS, we determined the MetS group had significantly higher levels of fasting serum C-peptide and high-sensitivity C-reactive protein, and a significantly lower level of serum adiponectin. However, the prevalence of coronary heart disease, brain infarction, or peripheral arterial disease was not significantly different between these groups. On the other hand, the prevalence of microangiopathy in the group with MetS was significantly higher than in that without MetS, and became significantly higher along with an increase in duration. This study clarifies the prevalence of MetS in Japanese type 2 diabetic patients, and suggests that MetS is associated with microangiopathy rather than macroangiopathy in Japanese type 2 diabetic patients.

Topics: Age of Onset; Aged; Body Mass Index; C-Peptide; Chronic Disease; Diabetes Mellitus, Type 2; Female; Humans; Japan; Male; Metabolic Syndrome; Middle Aged; Prevalence; Vascular Diseases

The influence of albuminuria and proliferative retinopathy on concentration of serum lipoprotein (a) was examined cross-sectionally in 90 Type 1 diabetic patients. Concentrations of lipoprotein (a) were less in those with normoalbuminuria (90 (8-882) (median (range] U l-1) than in those with micro- or macro-albuminuria (137 (19-1722) U l-1, p less than 0.05). The prevalence of patients whose lipoprotein (a) concentrations were greater than 200 U l-1 was also greater (45% vs 24%, p = 0.03) among patients with albuminuria, but no difference was found between the microalbuminuric and macroalbuminuric groups (53 and 41%, respectively), or between those with or without proliferative retinopathy. The present finding that lipoprotein (a) concentrations may be increased at an early stage of diabetic renal disease may in part account for the excess ischaemic heart disease associated with diabetic nephropathy.

Topics: Albuminuria; Apolipoproteins B; Biomarkers; Blood Glucose; Blood Pressure; C-Peptide; Cholesterol; Cholesterol, HDL; Cholesterol, LDL; Coronary Disease; Diabetes Mellitus, Type 1; Diabetic Angiopathies; Diabetic Retinopathy; Female; Glycated Hemoglobin; Humans; Lipoprotein(a); Lipoproteins; Male; Middle Aged; Triglycerides; Vascular Diseases