Indications

General

• Abnormal cholesterol levels

• Diabetes

• Heart disease

• High blood pressure

• Obesity

• Polycystic ovary syndrome (PCOS)

• Pre-diabetes

Overview

High fasting insulin levels are a good indicator of insulin resistance, whether or not the patient shows glucose intolerance. Insulin resistance occurs when the cellular response to the presence of insulin is impaired, resulting in a reduced ability of tissues to take up glucose for energy production. Chronically high insulin levels are seen as the body attempts to normalize blood sugar levels. The normal range for fasting insulin is 1 – 15 µIU/mL, but levels between 1 and 8 µIU/mL are optimal. Blood levels of insulin 2 hours after a meal are now becoming an important indicator of both diabetes progression and cardiovascular disease risk. In non-diabetics, elevated postprandial insulin may be a better marker of cardiovascular disease risk than fasting insulin. In individuals with diabetes, postprandial levels become lower as diabetes progresses and beta-cell responsiveness deteriorates, indicating worsening of blood sugar control. In nondiabetics, whose pancreatic beta cell function is normal, insulin levels usually return to normal (1-15 µIU/mL) within 2 hours after eating a typical breakfast meal. Elevated postprandial insulin levels have been strongly linked with coronary artery disease risk in non-diabetics.

Practical

Specimen requirements:

Bloodspot

Average processing time:

10 - 14 days

Research regarding vailidity (what is tested for)

• Albarrak AI, Luzio SD, Chassin LJ, et al. Associations of glucose control with insulin sensitivity and pancreatic beta-cell responsiveness in newly presenting type 2 diabetes. J Clin Endocrinol Metab 2002;87:198-203.

• Baltali M, Korkmaz ME, Kiziltan HT, et al. Association between postprandial hyperinsulinemia and coronary artery disease among nondiabetic women: a case control study. Int J Cardiol 2003;88:215-21.

• Karabulut A, Iltumur K, Toprak N, et al. Insulin response to oral glucose loading and coronary artery disease in nondiabetics. Int Heart J 2005;46:761-70.

• Laakso M. How good a marker is insulin level for insulin resistance? Am. J. Epidemiol., 1993; 137: 959- 965.

• Shim WS, Kim SK, Kim HJ, et al. Decrement of postprandial insulin secretion determines the progressive nature of type-2 diabetes. Eur J Endocrinol 2006;155:615-22.

Research regarding reliability (methodology used)

• Buttler N, et al. Development of a bloodspot assay for insulin. Clinica Chimica Acta., 2001; 310: 141-150.

• Dowlati. B, Dunhardt. P et. Al. Quantification of insulin in dried blood spots. J. Lab. Clin. Med., 1998; 131: 370.