(ĭn′sū-lĭn-ās) An enzyme that degrades or inactivates insulin.
ABBR: IAA. Antibodies to the hormone insulin. They are, in addition to antibodies to glutamic acid decarboxylase and protein tyrosine phosphatase-like molecules, one of the markers of type 1 diabetes mellitus or latent autoimmune diabetes in adults.
(ĭn-sū-lĭn-ē′mē-ă) [L. insula, island, + Gr. haima, blood] Hyperinsulinemia.
(ĭn″sū-lĭn″ō-jĕn′ĭk) [″ + Gr. gennan, to produce] 1. Caused by insulin whether administered therapeutically or produced naturally by the pancreas. 2. Pert. to the production of insulin.
(in″sŭ-lĭ-nō′mă) [insulin + -oma] An insulin-secreting tumor of the pancreas that causes potentially life-threatening hypoglycemia.
INCIDENCE: LOW blood sugars are common occurrences in people treated with insulin and some hypoglycemic pills, but insulinomas are rare. The estimated incidence is 1:1,250,000.
CAUSES: Insulin-secreting tumors develop from neuroendocrine (islet) cells in the pancreas or the liver.
SYMPTOMS AND SIGNS: Symptoms of low blood sugar include confusion, dizziness, near-fainting or fainting, nightmares, palpitations, diaphoresis, and, eventually, if blood sugars continue to fall and the brain is deprived of glucose, seizures, coma, or death.
DIAGNOSIS: Supervised fasting is the key to both diagnosis and patient care. A patient who is suspected of having an insulinoma is admitted to a closely supervised hospital ward, where caloric consumption is prohibited, and vital signs and plasma glucose levels are monitored carefully. Typically, after the patient begins to fast, venous blood glucose is drawn every 4 hr until it begins to decline. If plasma glucose levels drop, blood sugars are checked at decreasing intervals (every 2 hr, then hourly, then every half hour, etc.) until blood glucose levels drop to very low levels or the patient experiences symptoms of a low blood sugar. If hypoglycemia does not occur within 48 hr of supervised fasting, insulinoma is excluded. If blood glucose levels drop below 45 mg/dL and the patient has symptoms of hypoglycemia, or the blood sugar drops below 40 mg/dL on two consecutive measurements, the fast is aborted. Plasma C-peptide levels and insulin levels are assessed by the laboratory whenever blood sugars drop below normal. The ratio of plasma insulin to glucose is used to indicate the biochemical presence of an insulin-secreting tumor. Nonbiochemical means of identifying an insulinoma include endoscopic ultrasonography of the pancreas and pancreatic scintigraphy.
TREATMENT: Exploratory surgery is used to identify and remove the responsible tumor. SEE: hypoglycemia; neuroglycopenia.
Any of several diabetic medications, such as metformin or the thiazolidinediones, that improve the sensitivity of cells to the metabolic effects of insulin.