Biomaterial Database

Measurement of serum C-peptide immunoreactivity by radioimmunoassay in insulin-dependent diabetics. 1980

M S Kumar, and O P Schumacher, and S D Deodhar

A radioimmunoassay for C-peptide utilizing synthetic C-peptide as an antigen and tyrosylated synthetic C-peptide for iodination was evaluated for its clinical use. Mean fasting C-peptide levels in 24 normal subjects was 2.6 +/- 0.8 ng/ml. During the oral glucose tolerance test, baseline C-peptide in five normal subjects was 1.5 +/- 0.8 ng/ml, and at 60 min was 5.6 +/- 1.6 ng/ml. For two insulin-dependent diabetic patients, diagnoses of factitious hypoglycemia were documented on the basis of simultaneous free insulin and C-peptide determinations. Sera from 24 insulin-dependent diabetics were analyzed for free and total immunoreactive C-peptide and insulin levels. For 20% of juvenile and 64% of maturity-onset diabetics, the presence of proinsulin-like material bound to insulin antibodies was demonstrated by measurement in unextracted serum. This accounted for 20% to 100% of total C-peptide immunoreactivity in these patients. Simple polyethylene glycol precipitation of immune complexes and the measurement of free immunoreactive C-peptide in the supernatant demonstrated subnormal levels (less than 0.5 ng/ml) in all juvenile diabetics and normal levels (1.8 +/- 1.3 ng/ml) in 70% of maturity-onset diabetics.

UI	MeSH Term	Description	Entries
D007003	Hypoglycemia	A syndrome of abnormally low BLOOD GLUCOSE level. Clinical hypoglycemia has diverse etiologies. Severe hypoglycemia eventually lead to glucose deprivation of the CENTRAL NERVOUS SYSTEM resulting in HUNGER; SWEATING; PARESTHESIA; impaired mental function; SEIZURES; COMA; and even DEATH.	Fasting Hypoglycemia,Postabsorptive Hypoglycemia,Postprandial Hypoglycemia,Reactive Hypoglycemia,Hypoglycemia, Fasting,Hypoglycemia, Postabsorptive,Hypoglycemia, Postprandial,Hypoglycemia, Reactive
D007328	Insulin	A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).	Iletin,Insulin A Chain,Insulin B Chain,Insulin, Regular,Novolin,Sodium Insulin,Soluble Insulin,Chain, Insulin B,Insulin, Sodium,Insulin, Soluble,Regular Insulin
D007330	Insulin Antibodies	Antibodies specific to INSULIN.	Antibodies, Insulin
D010455	Peptides	Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS.	Peptide,Polypeptide,Polypeptides
D011863	Radioimmunoassay	Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.	Radioimmunoassays
D002096	C-Peptide	The middle segment of proinsulin that is between the N-terminal B-chain and the C-terminal A-chain. It is a pancreatic peptide of about 31 residues, depending on the species. Upon proteolytic cleavage of proinsulin, equimolar INSULIN and C-peptide are released. C-peptide immunoassay has been used to assess pancreatic beta cell function in diabetic patients with circulating insulin antibodies or exogenous insulin. Half-life of C-peptide is 30 min, almost 8 times that of insulin.	Proinsulin C-Peptide,C-Peptide, Proinsulin,Connecting Peptide,C Peptide,C Peptide, Proinsulin,Proinsulin C Peptide
D003920	Diabetes Mellitus	A heterogeneous group of disorders characterized by HYPERGLYCEMIA and GLUCOSE INTOLERANCE.
D003922	Diabetes Mellitus, Type 1	A subtype of DIABETES MELLITUS that is characterized by INSULIN deficiency. It is manifested by the sudden onset of severe HYPERGLYCEMIA, rapid progression to DIABETIC KETOACIDOSIS, and DEATH unless treated with insulin. The disease may occur at any age, but is most common in childhood or adolescence.	Diabetes Mellitus, Brittle,Diabetes Mellitus, Insulin-Dependent,Diabetes Mellitus, Juvenile-Onset,Diabetes Mellitus, Ketosis-Prone,Diabetes Mellitus, Sudden-Onset,Diabetes, Autoimmune,IDDM,Autoimmune Diabetes,Diabetes Mellitus, Insulin-Dependent, 1,Diabetes Mellitus, Type I,Insulin-Dependent Diabetes Mellitus 1,Juvenile-Onset Diabetes,Type 1 Diabetes,Type 1 Diabetes Mellitus,Brittle Diabetes Mellitus,Diabetes Mellitus, Insulin Dependent,Diabetes Mellitus, Juvenile Onset,Diabetes Mellitus, Ketosis Prone,Diabetes Mellitus, Sudden Onset,Diabetes, Juvenile-Onset,Diabetes, Type 1,Insulin Dependent Diabetes Mellitus 1,Insulin-Dependent Diabetes Mellitus,Juvenile Onset Diabetes,Juvenile-Onset Diabetes Mellitus,Ketosis-Prone Diabetes Mellitus,Sudden-Onset Diabetes Mellitus
D005260	Female		Females
D005951	Glucose Tolerance Test	A test to determine the ability of an individual to maintain HOMEOSTASIS of BLOOD GLUCOSE. It includes measuring blood glucose levels in a fasting state, and at prescribed intervals before and after oral glucose intake (75 or 100 g) or intravenous infusion (0.5 g/kg).	Intravenous Glucose Tolerance,Intravenous Glucose Tolerance Test,OGTT,Oral Glucose Tolerance,Oral Glucose Tolerance Test,Glucose Tolerance Tests,Glucose Tolerance, Oral