28.2 Insulin and Non-Insulin Injectable Diabetes Drugs

Insulin and Non-Insulin Injectable Diabetes Drugs

Insulin vs Non-Insulin Injectables

Insulin is a hormone produced by the beta cells of the pancreas. Its primary job is regulating blood glucose levels. In diabetes management, exogenous insulin is used to treat both type 1 and type 2 diabetes mellitus. It's administered subcutaneously, and the different formulations are categorized by how quickly they start working, when they peak, and how long they last:

• Rapid-acting (insulin lispro, insulin aspart): Onset within 10–15 minutes, peak at 1–2 hours, duration 3–5 hours. Taken right before or with meals.
• Short-acting (regular insulin): Onset within 30–60 minutes, peak at 2–4 hours, duration 6–8 hours. Usually given 30 minutes before meals. This is also the only insulin that can be given IV.
• Intermediate-acting (NPH insulin): Onset within 1–2 hours, peak at 4–12 hours, duration 12–18 hours. Often combined with rapid- or short-acting insulin.
• Long-acting (insulin glargine, insulin detemir): Onset within 1–2 hours, relatively peakless (glargine) or mild peak, duration up to 24 hours. Provides a basal level of insulin throughout the day.

Dosage is always individualized based on the patient's blood glucose readings, diet, activity level, and overall response.

Non-insulin injectable diabetes medications target blood glucose through different mechanisms than insulin itself:

• GLP-1 receptor agonists (exenatide, liraglutide, dulaglutide, semaglutide): These are incretin mimetics, meaning they mimic the incretin hormones your gut releases after eating. They stimulate insulin secretion only when blood glucose is elevated (glucose-dependent), inhibit glucagon release, slow gastric emptying, and promote satiety. This glucose-dependent action means the risk of hypoglycemia is lower compared to insulin when used alone. They're administered subcutaneously for type 2 diabetes. Some formulations are given daily, others weekly.
• Amylin analogs (pramlintide): Pramlintide is a synthetic form of amylin, a hormone normally co-secreted with insulin from beta cells. It slows gastric emptying, suppresses postprandial glucagon secretion, and promotes satiety. It's administered subcutaneously as an adjunct to mealtime insulin in both type 1 and type 2 diabetes, not as a standalone therapy.

Actions, Side Effects, and Interactions

Insulin

• Actions: Lowers blood glucose by facilitating glucose uptake into cells (especially muscle and fat tissue) and by inhibiting hepatic glucose production (gluconeogenesis and glycogenolysis).
• Side effects: Hypoglycemia is the most significant and dangerous side effect. Weight gain is common with ongoing use. Lipodystrophy (either hypertrophy or atrophy of subcutaneous fat) can develop at injection sites that aren't rotated properly.
• Interactions:
  • Drugs that increase hypoglycemic effect: sulfonylureas, fibrates, salicylates, ACE inhibitors, MAOIs, alcohol
  • Drugs that decrease hypoglycemic effect: corticosteroids, thyroid hormones, sympathomimetics (like epinephrine), thiazide diuretics

GLP-1 Receptor Agonists

• Actions: Stimulate glucose-dependent insulin secretion, inhibit glucagon release, slow gastric emptying, and promote satiety (which often leads to weight loss).
• Side effects: GI effects are the most common, especially nausea, vomiting, and diarrhea. These tend to be worst when starting the medication and often improve over time. Injection site reactions can occur. There's an increased risk of pancreatitis, so patients should be educated to report severe, persistent abdominal pain. Semaglutide and liraglutide carry a boxed warning for risk of thyroid C-cell tumors (based on animal studies), so they're contraindicated in patients with a personal or family history of medullary thyroid carcinoma or MEN 2 syndrome.
• Interactions: Because they slow gastric emptying, GLP-1 agonists may delay the absorption of oral medications. Advise patients to take oral meds at least 1 hour before the GLP-1 injection when timing matters.

Amylin Analogs (Pramlintide)

• Actions: Slow gastric emptying, suppress postprandial glucagon secretion, and promote satiety.
• Side effects: Nausea is the most common side effect. Hypoglycemia is a significant risk because pramlintide is always used alongside insulin. When starting pramlintide, the mealtime insulin dose is typically reduced by 50% to lower this risk.
• Interactions: Increased risk of hypoglycemia when combined with insulin or insulin secretagogues. Because it slows gastric emptying, it can also affect absorption of other oral medications.

Nursing Considerations

Assessment

• Check blood glucose levels before administration.
• Assess for signs and symptoms of hypoglycemia (tremors, diaphoresis, tachycardia, confusion) or hyperglycemia (polyuria, polydipsia, polyphagia, fruity breath).
• Review the patient's current medication list for interactions.

Preparation

1. Verify the medication order, including type, dose, and timing.
2. Select an appropriate injection site and rotate sites systematically to prevent lipodystrophy.
3. Use proper aseptic technique when preparing the injection.
4. For NPH insulin, gently roll the vial between your palms to resuspend it. Never shake it, as this can damage the insulin protein and cause inaccurate dosing.
5. When mixing insulins in one syringe (e.g., regular + NPH), always draw up the clear (regular) insulin first, then the cloudy (NPH). Remember: "clear before cloudy."

Administration

• Administer at the prescribed time and by the correct route (subcutaneous for all; regular insulin is the only type that can also be given IV).
• Rapid-acting insulin should be given within 15 minutes of a meal. Short-acting (regular) insulin is typically given 30 minutes before eating.
• Pramlintide must be injected separately from insulin and at a different site.
• Observe the patient for adverse reactions after administration.

Monitoring

• Monitor blood glucose levels regularly and report trends to the provider for dosage adjustments.
• Assess injection sites for signs of infection, inflammation, or lipodystrophy.
• Track HbA1c levels (typically every 3 months) to evaluate long-term glucose control.
• For patients on GLP-1 agonists, monitor for signs of pancreatitis (severe abdominal pain radiating to the back, nausea/vomiting).

Documentation

• Record medication administration including time, dose, route, and injection site.
• Document the patient's blood glucose level, response to the medication, and any adverse reactions.

Patient Education

Proper Injection Technique

• Demonstrate appropriate injection sites: abdomen (preferred for fastest absorption), thighs, upper arms, and buttocks.
• Teach systematic site rotation. Using the same spot repeatedly causes lipodystrophy, which then affects how well the medication absorbs.
• Instruct on proper aseptic technique and safe disposal of needles and syringes in a sharps container.
• Patients should never share insulin pens, even with a new needle, due to risk of bloodborne pathogen transmission.

Medication Storage

• Store unopened insulin and GLP-1 receptor agonists in the refrigerator (36–46°F / 2–8°C).
• Once opened, most can be stored at room temperature (below 86°F / 30°C) and used within the manufacturer's specified time frame (typically 28 days for most insulins, though this varies by product).
• Protect all medications from extreme temperatures and direct sunlight. Insulin that has been frozen should be discarded.

Hypoglycemia Management

Teach patients to recognize the signs of hypoglycemia: shakiness, sweating, tachycardia, confusion, irritability, and hunger. For mild to moderate hypoglycemia, use the 15-15 rule:

1. Consume 15 grams of fast-acting carbohydrates (e.g., 4 oz juice, 3–4 glucose tablets, or 1 tablespoon of honey).
2. Wait 15 minutes, then recheck blood glucose.
3. If still below 70 mg/dL, repeat step 1.
4. Once blood glucose normalizes, eat a small snack with protein and complex carbohydrates to prevent another drop.

For severe hypoglycemia (unconsciousness, seizures, inability to swallow), the patient cannot take anything by mouth. A family member or caregiver should administer glucagon (IM or intranasal) and call emergency services.

Lifestyle Modifications

• Encourage regular blood glucose monitoring and keeping a log to share with the healthcare team.
• Emphasize the importance of consistent meal timing and a balanced diet, especially when on insulin.
• Discuss how exercise lowers blood glucose and may require insulin dose adjustments or a pre-exercise snack.
• Address the impact of illness (sick-day rules), stress, and travel (especially across time zones) on blood glucose management.

Follow-Up Care

• Stress the importance of regular check-ups, including HbA1c monitoring, kidney function tests, and eye exams.
• Encourage patients to report any adverse reactions, new symptoms, or difficulty managing their blood glucose to their healthcare team promptly.