Insulin

Synonym/Acronym

N/A

Rationale

To assess the amount of insulin secreted in response to blood glucose to assist in diagnosis of insulinomas, types of hypoglycemia, and insulin-resistant pathologies.

Patient Preparation

There are no fluid or activity restrictions unless by medical direction. The patient should have fasted and refrained, with medical direction, from taking insulin, other oral hypoglycemic drugs, or multivitamins/dietary supplements containing biotin (vitamin B₇) for at least 8 hr before specimen collection.

Normal Findings

Method: Electrochemiluminescence Immunoassay.

	Insulin	SI Units (Conventional Units × 6.945)
Fasting	3–25 micro-international units/L	20.8–173.6 pmol/L

Critical Findings and Potential Interventions ⬆ ⬇

Overview ⬆ ⬇

(Study type: Blood collected in a gold-, red-, or red/gray-top tube; related body system: Endocrine system.)

Insulin is a hormone secreted by the beta cells of the pancreatic islets of Langerhans in response to elevated blood glucose levels. Its overall effect is to help regulate the metabolism of glucose. Specifically, insulin decreases blood levels of glucose by promoting transport of glucose into the liver and muscles to be stored as glycogen. Insulin also participates in regulation of the processes required for metabolism of fats, carbohydrates, and proteins.

Diabetes is a group of diseases characterized by hyperglycemia, or elevated glucose levels. Type 1 diabetes can result from a defect in insulin secretion due to destruction of the beta cells of the pancreas. Type 2 diabetes can result from a defect in insulin action or a combination of defects in secretion and action (insulin resistance). For additional information regarding insulin and the onset of diabetes, refer to the studies titled “C-Peptide,” “Glucose,” “Glucose Tolerance Tests,” and “Insulin Antibodies.”

Indications ⬆ ⬇

Assist in the diagnosis of early or developing type 2 diabetes, as indicated by excessive production of insulin in relation to blood glucose levels (best shown with glucose tolerance tests or 2-hr postprandial tests). For additional information regarding screening guidelines and management of diabetes, refer to the study titled “Glucose.”
Assist in the diagnosis of insulinoma, as indicated by sustained high levels of insulin and absence of blood glucose–related variations when performed and interpreted in conjunction with C-peptide.
Evaluate fasting hypoglycemia of unknown cause.
Evaluate postprandial hypoglycemia of unknown cause.
Evaluate uncontrolled type 1 diabetes.

Contraindications ⬆ ⬇

Interfering Factors ⬆ ⬇

Drugs and other substances that may increase insulin levels include albuterol, amino acids, beclomethasone, betamethasone, broxaterol, calcium gluconate, cannabis, chlorpropamide, glibornuride, glipizide, glisoxepide, glucagon, glyburide, ibopamine, insulin, oral contraceptives, pancreozymin, prednisolone, prednisone, rifampin, terbutaline, tolazamide, tolbutamide, trichlormethiazide, and verapamil.
Drugs and other substances that may decrease insulin levels include acarbose, calcitonin, cimetidine, clofibrate, diltiazem, doxazosin, enalapril, enprostil, ether, hydroxypropyl methylcellulose, metformin, niacin, nifedipine, nitrendipine, octreotide, phenytoin, propranolol, and psyllium.
Administration of insulin or oral hypoglycemic drugs within 8 hr of the test can lead to falsely elevated levels.
Biotin in the blood specimen can cause discrepancies in either direction depending on the method.
Hemodialysis destroys insulin and affects test results.

Potential Medical Diagnosis: Clinical Significance of Results ⬆ ⬇

Increased In

Acromegaly (related to excess production of growth hormone, which increases insulin levels)
Alcohol use (related to stimulation of insulin production)
Cushing syndrome (related to overproduction of cortisol, which increases insulin levels)
Excessive administration of insulin
Insulin- and proinsulin-secreting tumors (insulinomas)
Obesity (related to development of insulin resistance; body does not respond to insulin being produced)
Persistent hyperinsulinemic hypoglycemia (collection of hypoglycemic disorders of infants and children)
Reactive hypoglycemia in developing diabetes
Severe liver disease

Decreased In

Beta cell failure (pancreatic beta cells produce insulin; therefore, damage to these cells will decrease insulin levels)
Type 1 diabetes or type 2 diabetes (related to lack of endogenous insulin)

Nursing Implications ⬆

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

Explain that a blood sample is needed for the test. Multiple specimens may be required.
Discuss how this test can assist in the evaluation of low blood sugar. To assess for hypoglycemia, serial specimens for insulin levels are collected in conjunction with glucose levels after administration of a 75-g glucose load.
An abnormal insulin response and impaired glucose tolerance may be associated with diabetes.

After the Study: Implementation & Evaluation Potential Nursing Actions

Avoiding Complications

Note that the patient may have difficulty drinking the extremely sweet glucose beverage and become nauseous.
Emphasize how good management of glucose levels delays the onset and slows the progression of diabetic retinopathy, nephropathy, and neuropathy. Unmanaged diabetes can cause multiple health issues, including diabetic kidney disease, amputation of limbs, and ultimately, death.
Discuss the advantages of attending support group meetings to learn how to manage the disease from other people with diabetes. Emphasize the importance of adhering to the recommended therapeutic regime to manage diabetes.

Treatment Considerations

Interventions/actions include the following: Emphasize the importance of reporting signs and symptoms of hypoglycemia (weakness, confusion, diaphoresis, rapid pulse) or hyperglycemia (thirst, polyuria, hunger, lethargy). Demonstrate how to perform a self-check glucose accurately and to correctly self-administer insulin or to take oral antihyperglycemic drugs with return demonstration.

Nutritional Considerations

Instruct the patient in the nutritional management of diabetes. Encourage consultation with a registered dietitian who is a certified diabetes educator. Explain that a variety of dietary patterns are beneficial for people with diabetes.
Patients who adhere to dietary recommendations report a better general feeling of health, better weight management, better management of glucose and lipid values, and improved use of insulin. There is no “diabetic diet”; however, many meal-planning approaches with nutritional goals are endorsed by the American Diabetes Association (ADA).

Clinical Judgement

Consider how to overcome cultural barriers toward nutritional changes needed to improve health.

Follow-Up Evaluation and Desired Outcomes

Acknowledges contact information provided for the ADA (www.diabetes.org), American Heart Association (www .heart.org/HEARTORG), National Heart, Lung, and Blood Institute (www.nhlbi .nih.gov), National Institute of Diabetes and Digestive and Kidney Disease (www.niddk.nih.gov), and U.S. Department of Agriculture’s resource for nutrition (www.myplate.gov).

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