Pharmacologic Profile

General Use

Insulin is used in the management of type 1 diabetes mellitus. It may also be used in type 2 diabetes mellitus when diet and/or oral medications fail to adequately control blood sugar. The choice of insulin preparation (rapid-acting, intermediate-acting, long-acting) depends on the degree of control desired, daily blood glucose fluctuations, and history of previous reactions. Oral agents non-insulin injectable agents are used primarily in type 2 diabetes mellitus. Oral agents are used when diet therapy alone fails to control blood glucose or symptoms or when patients are not amenable to using insulin or another injectable agent. Some oral agents may be used with insulin.

General Action and Information

Insulin, a hormone produced by the pancreas, lowers blood glucose by ↑ transport of glucose into cells and promotes the conversion of glucose to glycogen. It also promotes the conversion of amino acids to proteins in muscle, stimulates triglyceride formation, and inhibits the release of free fatty acids. Sulfonylureas, nateglinide, repaglinide, the dipeptidyl peptidase 4 (DPP-4) inhibitors (e.g. sitagliptin), and the glucagon-like peptide-1 (GLP-1) receptor agonists (e.g. exenatide) ↓ blood glucose by stimulating endogenous insulin secretion by beta cells of the pancreas and by ↑ sensitivity to insulin at intracellular receptor sites. Intact pancreatic function is required. Acarbose and miglitol delay digestion of ingested carbohydrates, thus ↓ blood glucose, especially after meals. The thiazolidinediones (e.g. pioglitazone) and metformin ↑ insulin sensitivity. The sodium-glucose transporter 2 (SGLT2) inhibitors (e.g. empagliflozin) inhibit the reabsorption of glucose in the proximal renal tubule, thereby ↑ the excretion of glucose in the urine.

Contraindications

Insulin—Hypoglycemia. Oral hypoglycemic agents—Hypersensitivity (cross-sensitivity with other sulfonylureas and sulfonamides may exist). Hypoglycemia. Type 1 diabetes. Avoid use in patients with severe kidney, liver, thyroid, and other endocrine dysfunction. Should not be used in pregnancy or lactation. DPP–4 inhibitors—Type 1 diabetes. GLP-1 agonists—Personal or family history of medullary thyroid carcinoma. Multiple Endocrine Neoplasia syndrome type 2. SGLT2 inhibitors—Severe renal impairment.

Precautions

Insulin—Infection, stress, or changes in diet may alter requirements. Oral hypoglycemic agents—Use cautiously in geriatric patients. Dose ↓ may be necessary. Infection, stress, or changes in diet may alter requirements. Use sulfonylureas with caution in patients with a history of cardiovascular disease. Metformin may cause lactic acidosis. DPP–4 inhibitors—Use cautiously in patients with renal impairment, history of pancreatitis, or history of angioedema to another DPP-4 inhibitor. GLP-1 agonists—Use cautiously in patients with a history of pancreatitis or history of angioedema to another GLP-1 agonist. SGLT2 inhibitors—Use cautiously in patients with moderate renal impairment or history of pancreatitis. Hypovolemia, chronic kidney disease, HF, concurrent use of diuretics, NSAIDs, ACE inhibitors, or ARBs may ↑ risk of acute kidney injury. Previous amputation, peripheral vascular disease, neuropathy, or diabetic foot infection may ↑ risk of lower limb amputation.

Interactions

Insulin—Additive hypoglycemic effects with oral hypoglycemic agents. Oral hypoglycemic agents—Ingestion of alcohol may result in disulfiram-like reaction with some agents. Alcohol, corticosteroids, rifampin, glucagon, and thiazide and loop diuretics may ↓ effectiveness. Anabolic steroids, chloramphenicol, MAO inhibitors, most NSAIDs, salicylates, sulfonamides, and warfarin may ↑ hypoglycemic effect. Beta blockers may produce hypoglycemia and mask signs and symptoms of hypoglycemia. DPP–4 inhibitors—Use with insulin or sulfonylureas may ↑ hypoglycemic effect. GLP-1 agonists—Use with sulfonylureas may ↑ hypoglycemic effect. SGLT2 inhibitors—Use with insulin or sulfonylureas may ↑ hypoglycemic effect. NSAIDs, diuretics, ACE inhibitors, or ARBs may ↑ risk of acute kidney injury.

Nursing Implications

Assessment

• Observe patient for signs and symptoms of hypoglycemic reactions.
• Metformin, acarbose, miglitol, and the thiazolidinediones do not cause hypoglycemia when taken alone but may ↑ the hypoglycemic effect of other hypoglycemic agents.
• Patients who have been well controlled on metformin but develop illness or laboratory abnormalities should be assessed for ketoacidosis or lactic acidosis. Assess serum electrolytes, renal function, ketones, glucose, and, if indicated, blood pH and lactate and pyruvate levels. If either form of acidosis is present, discontinue metformin immediately and treat acidosis.
• Serum glucose and glycosylated hemoglobin should be monitored periodically throughout therapy to evaluate effectiveness of treatment.

Potential Nursing Diagnoses

• Imbalanced nutrition: more than body requirements (Indications)
• Deficient knowledge related to medication regimen (Patient/Family Teaching)
• Noncompliance (Patient/Family Teaching)

Implementation

• Patients stabilized on a diabetic regimen who are exposed to stress, fever, trauma, infection, or surgery may require sliding scale insulin. Withhold oral hypoglycemic agents and reinstitute after resolution of acute illness.
• Available in different types and strengths and from different species. Check type, species, source, dose, and expiration date with another licensed nurse. Do not interchange insulins without physician's order. Use only insulin syringes to draw up dose. Use only U100 syringes to draw up insulin lispro dose.

Patient/Family Teaching

• Explain to patient that medication controls hyperglycemia but does not cure diabetes. Therapy is long-term.
• Review signs of hypoglycemia and hyperglycemia with patient. If hypoglycemia occurs, advise patient to take a glass of orange juice or 2–3 tsp of sugar, honey, or corn syrup dissolved in water (glucose, not table sugar, if taking miglitol), and notify health care professional.
• Encourage patient to follow prescribed diet, medication, and exercise regimen to prevent hypoglycemic or hyperglycemic episodes.
• Instruct patient in proper testing of serum glucose and ketones.
• Advise patient to notify health care professional if nausea, vomiting, or fever develops; if unable to eat usual diet; or if blood glucose levels are not controlled.
• Advise patient to carry sugar or a form of glucose and identification describing medication regimen at all times.
• Insulin is the recommended method of controlling blood glucose during pregnancy. Counsel female patients to use a form of contraception other than oral contraceptives and to notify health care professional promptly if pregnancy is planned or suspected.
• Instruct patient on proper technique for administration; include type of insulin, equipment (syringe and cartridge pens), storage, and syringe disposal. Discuss the importance of not changing brands of insulin or syringes, selection and rotation of injection sites, and compliance with therapeutic regimen.
• Advise patient that concurrent use of alcohol may cause a disulfiram-like reaction (abdominal cramps, nausea, flushing, headache, and hypoglycemia).
• Explain to patient the risk of lactic acidosis and the potential need for discontinuation of metformin therapy if a severe infection, dehydration, or severe or continuing diarrhea occurs or if medical tests or surgery is required.

Evaluation/Desired Outcomes

• Control of blood glucose levels without the appearance of hypoglycemic or hyperglycemic episodes.