Endocrine & Diabetic Medications

Insulin Types: Onset, Peak & Duration

The single most-tested endocrine topic. Know the peak — that's when hypoglycemia is most likely.

Insulin lowers blood glucose by moving glucose into cells. The four categories are grouped by how fast they work and how long they last. The peak is the key number: it is when the risk of hypoglycemia is highest, so you must know when the client will eat.

Rapid-actingLispro (Humalog), aspart (NovoLog), glulisine (Apidra)

Onset: ~15 min · Peak: ~1 hr · Duration: 3–4 hr

Short-actingRegular (Humulin R, Novolin R)

Onset: ~30–60 min · Peak: 2–3 hr · Duration: 5–8 hr

Intermediate-actingNPH (Humulin N, Novolin N)

Onset: 1–2 hr · Peak: 4–12 hr · Duration: 12–18 hr

Long-actingGlargine (Lantus), detemir (Levemir), degludec (Tresiba)

Onset: 1–2 hr · Peak: No pronounced peak · Duration: ~24 hr

• Rapid-acting: give within ~15 minutes of a meal — the tray must be there. Onset is so fast that giving it without food coming causes hypoglycemia.
• Regular insulin is the only insulin given IV (used in DKA) and the only short-acting one you'll usually mix.
• NPH is the cloudy insulin — it must be gently rolled (not shaken) to resuspend it. Its wide peak (4–12 hr) is a common hypoglycemia window.
• Long-acting (glargine/detemir): a steady basal level with no real peak, given once daily. Never mix it with another insulin.

Insulin Administration, Mixing & Storage

Clear before cloudy, the right syringe, and where to keep the vial.

Mixing NPH + Regular

When NPH (cloudy) and Regular (clear) are ordered together, they can be drawn into one syringe. The order matters:

Administration Basics

• Use an insulin syringe measured in units (never a tuberculin or regular syringe). U-100 insulin = 100 units/mL.
• Give subcutaneously at a 90° angle (45° if thin); do not aspirate or massage the site.
• Rotate sites within one anatomic area to prevent lipohypertrophy; the abdomen absorbs fastest and most consistently.
• Two nurses often verify insulin doses — insulin is a high-alert medication.

Storage

• Unopened insulin: store in the refrigerator.
• The vial or pen in use can be kept at room temperature (typically up to ~28 days) — giving cold insulin is more painful.
• Never use insulin that is clumped, frosted, or discolored. Do not freeze insulin.

Oral Antidiabetics (Type 2 Diabetes)

Metformin is first-line; sulfonylureas are the ones that actually cause hypoglycemia.

BiguanideMetformin (Glucophage)

First-line for type 2. Does NOT cause hypoglycemia alone. Hold 24–48 hr around IV contrast dye (lactic acidosis / kidney risk). Side effects: GI upset, metallic taste.

SulfonylureasGlipizide, glyburide, glimepiride

Stimulate the pancreas to release insulin → can cause hypoglycemia. Avoid alcohol (disulfiram-like reaction). Take before meals.

MeglitinidesRepaglinide, nateglinide

Short-acting; take with meals — skip the dose if the meal is skipped.

DPP-4 inhibitorsSitagliptin (the "-gliptins")

Low hypoglycemia risk. Watch for pancreatitis and joint pain.

SGLT2 inhibitorsEmpagliflozin, dapagliflozin (the "-gliflozins")

Excrete glucose in urine → risk of genital/urinary infections and dehydration. Teach perineal hygiene and fluids.

ThiazolidinedionesPioglitazone (the "-glitazones")

Can cause fluid retention — avoid in heart failure; monitor for edema and weight gain.

Non-Insulin Injectables

The "-tides" — incretin mimetics that also slow gastric emptying.

• GLP-1 receptor agonists (the "-tides"): exenatide, liraglutide, semaglutide, dulaglutide. They lower glucose, slow gastric emptying, and promote satiety (weight loss). Given subcutaneously.
• Side effects: nausea (most common, often improves), and a risk of pancreatitis. Boxed warning for thyroid C-cell tumors — avoid with a personal/family history of medullary thyroid cancer or MEN-2.
• Because they slow gastric emptying, they can affect the absorption of oral drugs.
• Amylin analog (pramlintide): used with insulin; never mixed in the same syringe with insulin.

Hypoglycemia & Sick-Day Rules

The fastest, highest-priority intervention in all of endocrine pharmacology.

Recognize Hypoglycemia (<70 mg/dL)

Cold and clammy → need some candy. Signs: sweating, shakiness, tachycardia, hunger, confusion, irritability. It comes on fast and is an emergency because the brain needs glucose.

The Rule of 15 (conscious, can swallow)

• Give 15 g of fast-acting carbohydrate — 4 oz juice or regular soda, 3–4 glucose tablets, or 1 Tbsp honey.
• Wait 15 minutes, then recheck the blood glucose. Repeat if still below 70.
• Once normal, give a snack with protein and carbohydrate to prevent a repeat drop.

If Unconscious / Cannot Swallow

• Give glucagon IM/SubQ (or intranasal), or IV dextrose (D50) in a hospital.
• Nothing by mouth if the client cannot safely swallow — aspiration risk.
• Turn the client on their side; glucagon can cause vomiting.

Sick-Day Rules (teach clients)

• Never stop insulin when ill, even if not eating — illness raises blood glucose.
• Monitor glucose (and ketones in type 1) more often, and keep taking fluids.
• Notify the provider for persistent vomiting, high glucose, or ketones.

Thyroid Medications

Replace it when it's low; block it when it's high.

Hypothyroidism — Thyroid Replacement

• Levothyroxine (Synthroid): synthetic T4, taken for life.
• Take once daily in the morning, on an empty stomach, ~30–60 min before breakfast, at the same time daily.
• Separate from antacids, calcium, and iron (they reduce absorption).
• Full effect takes weeks; do not switch brands without provider approval.
• Too-high dose mimics hyperthyroidism: tachycardia, chest pain, nervousness, weight loss, insomnia, heat intolerance — report these.

Hyperthyroidism — Antithyroid Drugs

• Methimazole and propylthiouracil (PTU) block thyroid hormone production. PTU is preferred in the first trimester of pregnancy.
• Major risk: agranulocytosis — teach clients to report sore throat, fever, or signs of infection immediately.
• Effect is gradual (weeks). PTU also carries a risk of liver toxicity.
• Potassium iodide / Lugol's solution: dilute and give through a straw (stains teeth); used short-term before thyroid surgery.

Corticosteroids (Glucocorticoids)

The "-sone" drugs — powerful anti-inflammatories with big teaching points.

Glucocorticoids such as prednisone, prednisolone, methylprednisolone, dexamethasone, and hydrocortisone suppress inflammation and the immune response. They replace cortisol in adrenal insufficiency (Addison's) and treat many inflammatory conditions.

• Never stop abruptly — must be tapered to prevent acute adrenal crisis (the body has stopped making its own cortisol).
• Take with food (GI irritation/ulcers) and in the morning to mimic natural cortisol rhythm.
• Raises blood glucose — monitor, especially in diabetics.
• Masks signs of infection and increases infection risk — avoid sick contacts; report fever.
• Long-term effects: Cushingoid appearance (moon face, buffalo hump), weight gain/fluid retention, osteoporosis, muscle wasting, mood changes, thin skin, cataracts, and hypokalemia.

Other Endocrine Drugs

A few more that show up on the exam.

• Desmopressin (DDAVP): synthetic ADH for diabetes insipidus — reduces excessive urination. Watch for water intoxication / hyponatremia (headache, confusion, low sodium); monitor daily weight and I&O.
• Glucagon: raises blood glucose; the emergency drug for severe hypoglycemia when the client can't take oral sugar.
• Vasopressin: also used for diabetes insipidus and in some emergencies.
• Demeclocycline / vaptans (e.g., tolvaptan): used in SIADH (too much ADH) to promote water excretion.
• Bisphosphonates (alendronate) for osteoporosis: take with a full glass of water, first thing in the morning, and stay upright 30 minutes to prevent esophageal irritation.

Frequently Asked Questions

Common student questions on this topic.

Quick-Reference Cheatsheet

Every key point from this guide on a single printable page.