Insulin Human ELISA (Multispecies specificity)

Summary

Insulin, a polypeptide hormone with a molecular weight of 5800 Da, is secreted by the beta cells of the islets of Langerhans from the pancreas. Insulin possesses a wide spectrum of biological actions. It stimulates cellular glucose uptake, glucose oxidation, glycogenesis, lipogenesis, proteogenesis and the formation of DNA and RNA. Insulin plays a key role in the regulation of plasma glucose levels (hepatic output inhibition, stimulation of peripheral glucose utilisation). The resulting hypoglycemic effects of insulin are counterbalanced by hormones with hyperglycemic effects (glucagon, growth hormone, cortisol, epinephrin). Insulin secretion is mainly controlled by the plasma glucose levels : hyperglycemia induces a prompt and important increase in circulating insulin levels. Neural influences, as well as various metabolic and hormonal factors (amino acids, glucagon, gastrointestinal hormone) also participate to the control of insulin secretion. Type I (insulin dependent : “juvenile”) diabetes is due to a destruction of the beta cells, with a consequence of absolute lack of insulin. In type II (noninsulin-dependent : “maturity onset”) diabetes, insulin resistance may play an important role; however after several years of evolution, beta-cells failure may occur, leading to a relative insulinopenia requiring, in some cases, insulin administration. Insulin resistance is associated with high circulation levels of the hormone. The most common case of insulin resistance is represented by obesity. Various endocrinopathies (acromegaly, Cushing syndrome) as well as rare cases of insulin receptor defects or cases with anti-insulin receptor antibodies are associated with glucose intolerance or even diabetes due to insulin resistance. The determination of plasma insulin levels is an important parameter in the diagnosis of hypoglycemia. Insulin levels are high in cases of insulinoma (beta-cell tumor). Functional postprandial hypoglycemia may also be associated with inappropriate insulin release to carbohydrate intake. Insulin levels are determined either in the fasting state or during dynamic test :

1. stimulation test : carbohydrate rich meal, oral glucose tolerance test (OGTT), arginin infusion, tolbutamide or

other sulfonylureas administration.

2. inhibition test : fasting, somatostatine infusion

Clinical application of insulin determination

• Determination of the beta-cell reserve during glucose tolerance test or after a carbohydrate rich meal, as a

guide for the instauration of insulin therapy;

• Contribution to the diagnosis of insulin and non-insulin-dependent diabetes;
• Characterisation and follow-up of states of glucose intolerance;
• Diagnosis and study of cases of insulin resistance;
• Diagnosis of insulinoma and other causes of hypoglycemia.

Research topic

Animal studies, Diabetology - Insulin, C-Peptide, Proinsulin, Energy metabolism and body weight regulation

Assay format

Sandwich ELISA, Biotin-labelled antibody

Applications

Serum

Sample requirements

25 µl/well

Storage/Shipping

+4°C/ Wet ice

Calibration Curve

Calibration range

0.137 to 100 ng/ml

Intra-assay

human CV = 6.59–7.10%, rabbit CV = 2.51–9.08%, dog CV = 1.39–8.58%

Inter-assay

human CV = 6.86–11.86%

Spiking Recovery

human 93,28%, rabbit 104.25%, dog 137,3%

References to summary

• Best JD, Beard JC, Judzewitsch RG, Pfeifer MA, Porte D Jr, Halter JB. Chronic chlorpropamide therapy of noninsulin-dependent diabetes augments basal and stimulated insulin secretion by increasing islet sensitivity to glucose. J Clin Endocrinol Metab. 1982 Aug;55 (2):321-8
• Frier BM, Ashby JP, Nairn IM, Baird JD. Plasma insulin, C-peptide and glucagon concentrations in patients with insulin-independent diabetes treated with chlorpropamide. Diabete Metab. 1981 Mar;7 (1):45-9
• Hales CN, Clark PM, Temple R. Measurement of insulin secretion in type 2 diabetes: problems and pitfalls. Diabet Med. 1992 Jul;9 (6):503-12
• Hales CN, Temple RC, Carrington CA, Luzio SD, Owens DR, Schneider AE, Sobey WJ. Insulin deficiency in non-insulin-dependent diabetes. Lancet. 1989 Feb 11;1 (8633):293-5
• Hales CN, Yudkin JS, Schneider AE, Nagi DK, Clark PM, Temple RC. Radioimmunoassay may overestimate insulin in non-insulin-dependent diabetics. Clin Endocrinol (Oxf). 1990 Jun;32 (6):689-93
• Kosaka K, Hagura R, Kuzuya T. Insulin responses in equivocal and definite diabetes, with special reference to subjects who had mild glucose intolerance but later developed definite diabetes. Diabetes. 1977 Oct;26 (10):944-52
• Roth J, Kahn CR, Flier JS. Receptors, antireceptor antibodies and mechanisms of insulin resistance. N Engl J Med. 1979 Feb 22;300 (8):413-9
• Starr JI, Rubenstein AH, Juhn D, Mako ME. Measurement of serum proinsulin-like material: cross-reactivity of porcine and human proinsulin in the insulin radioimmunoassay. J Lab Clin Med. 1978 Apr;91 (4):683-92

By research topic:

• Animal studies
• Diabetology - Insulin, C-Peptide, Proinsulin
• Energy metabolism and body weight regulation

By molecule:

• Insulin