NCLEX Endocrine & Diabetes Review

Endocrine questions look intimidating because the vocabulary is dense, but they are built on one repeating idea: every gland makes too much or too little of a hormone, and the signs and symptoms follow directly from that. Once you can say what a hormone does, you can reason out the assessment findings instead of memorizing lists. This review covers the endocrine content that shows up most often on the NCLEX — diabetes and insulin, the two hyperglycemic emergencies, thyroid and adrenal disorders, and the antidiuretic hormone pair.

Start with the too-much / too-little framework

Before any disease name, ask two questions: what does this hormone do? and is there too much or too little of it? The clinical picture falls out of the answer.

• Thyroid hormone sets metabolic rate. Too much speeds everything up — tachycardia, weight loss, heat intolerance, diarrhea. Too little slows it down — bradycardia, weight gain, cold intolerance, constipation.
• Antidiuretic hormone (ADH) holds on to water. Too much and the patient is soaked inside; too little and the patient is dry inside.
• Cortisol raises glucose, retains sodium and water, and suppresses inflammation. Too much looks like Cushing’s; too little looks like Addison’s.
• Insulin moves glucose into cells. Too little and glucose stays in the blood; too much and the blood runs empty.

Work forward from the hormone every time — a disorder you have never reviewed is still reasonable if you know the hormone’s job and the direction it moved.

Type 1 vs type 2 diabetes

The NCLEX expects you to distinguish these confidently, because the teaching and the emergencies differ.

• Type 1 results from autoimmune destruction of the pancreatic beta cells, producing an absolute insulin deficiency. These patients require insulin to live, typically present younger, and are the group at risk for diabetic ketoacidosis.
• Type 2 is driven by insulin resistance with a relative deficiency. Onset is more gradual, management often begins with nutrition, activity, and oral agents, and the associated emergency is hyperosmolar hyperglycemic state.

Classic hyperglycemia findings are the three P’s — polyuria, polydipsia, and polyphagia — along with fatigue, blurred vision, and slow wound healing. Glucose that exceeds the renal threshold spills into the urine and pulls water with it, which is why urination and thirst rise together.

Hemoglobin A1C reflects average blood glucose over roughly the previous two to three months, so it checks long-term control rather than this morning’s reading. The American Diabetes Association sets a diagnostic threshold of 6.5% or higher, and a target below 7% is commonly cited for many nonpregnant adults — but targets are individualized based on age, comorbidities, and hypoglycemia risk.

Insulin: the onset and peak table worth memorizing

Insulin questions almost always hinge on timing. Peak is when hypoglycemia is most likely, so peak drives both your teaching and your monitoring.

• Rapid-acting (lispro, aspart, glulisine): onset roughly 15 minutes, peak about 1 hour. Food must be available when you give it — give it with the meal or just before.
• Short-acting regular insulin: onset about 30 minutes, peak roughly 2–3 hours. Give about 30 minutes before eating. Regular insulin is the only type given intravenously.
• Intermediate-acting NPH: onset 1–2 hours, peak roughly 4–12 hours. It is cloudy, and it is the one that requires gentle rolling to mix.
• Long-acting (glargine, detemir, degludec): relatively peakless basal coverage over roughly 24 hours. Do not mix long-acting insulin in a syringe with any other insulin.

When mixing regular with NPH in one syringe, draw the clear before the cloudy so the suspension never contaminates the regular vial. Also rotate injection sites within one anatomic region, and remember that exercise and skipped meals both lower glucose.

Hypoglycemia, and the two overnight patterns

Hypoglycemia is generally defined as a blood glucose below 70 mg/dL, and it is the more urgent extreme. Findings come from sympathetic activation and an underfed brain: shakiness, diaphoresis, tachycardia, pallor, hunger, irritability, confusion, and eventually seizures and loss of consciousness.

The classic memory line is “cold and clammy, need some candy; hot and dry, sugar high” — useful, but confirm with a glucose check when the question allows it.

The rule of 15 for a conscious patient who can swallow: give about 15 grams of fast-acting carbohydrate, wait 15 minutes, recheck the glucose, and repeat if it is still low. Follow with a longer-acting snack containing protein once the level is stable. If the patient is unconscious or unable to swallow safely, nothing goes in the mouth — glucagon or intravenous dextrose is indicated per protocol.

Two overnight patterns produce the same morning high and are frequently contrasted:

• Somogyi phenomenon: nocturnal hypoglycemia triggers counter-regulatory hormones and a rebound high by morning. The 2–3 a.m. glucose is low, and management usually means less evening insulin or a bedtime snack.
• Dawn phenomenon: an early-morning surge of growth hormone and cortisol raises glucose. The 2–3 a.m. check is normal or high, and management often means adjusting evening insulin upward.

The distinguishing action in both cases is the same: check the middle-of-the-night glucose.

DKA vs HHS

Both are hyperglycemic emergencies treated with fluids and insulin, and the NCLEX loves to make you separate them.

• Diabetic ketoacidosis is typically a type 1 event. With no insulin available, the body burns fat and generates ketones, producing a metabolic acidosis. Look for Kussmaul respirations (deep, rapid breathing that blows off carbon dioxide), a fruity breath odor, ketones in blood and urine, abdominal pain, and a low pH.
• Hyperosmolar hyperglycemic state is typically a type 2 event. Enough insulin remains to prevent significant ketosis, so there is no marked acidosis and no Kussmaul breathing, but glucose climbs far higher and profound dehydration produces altered mental status. Onset is slower and often follows an infection.

Priorities are consistent across both:

1. Fluids first. Isotonic intravenous fluid restores volume and perfusion; these patients are severely dehydrated.
2. Intravenous regular insulin by continuous infusion, per protocol.
3. Watch potassium relentlessly. Serum potassium may read normal or high on arrival even though total body potassium is depleted, and it falls as insulin drives potassium into cells. Insulin is typically held for a low potassium until it is replaced, with cardiac monitoring throughout.
4. Anticipate adding dextrose as glucose approaches roughly 250 mg/dL, so the insulin infusion can keep clearing ketones without causing hypoglycemia.

If an answer option offers insulin before any fluid in a severely dehydrated patient, look harder at the fluid option.

Thyroid and adrenal disorders

Hypothyroidism slows the body down; in primary disease, TSH is high and T4 is low. Teaching centers on levothyroxine: take it in the morning on an empty stomach, at the same time daily, separated from other medications, and usually for life. Report chest pain, palpitations, or insomnia, which suggest too high a dose. The extreme is myxedema coma.

Hyperthyroidism speeds it up, with low TSH and high T4 in Graves’ disease, plus possible exophthalmos and goiter. Provide a cool, quiet environment and a high-calorie diet without caffeine. Thyroid storm — high fever, severe tachycardia, agitation — is an emergency.

After a thyroidectomy, priorities are unusually testable: support the head and neck in semi-Fowler’s, keep emergency airway equipment at the bedside, check behind the neck for pooling blood, report worsening hoarseness or stridor immediately, and watch for hypocalcemia and tetany if parathyroid tissue was disturbed — tingling around the mouth and fingers, with positive Chvostek’s or Trousseau’s signs.

Addison’s disease (adrenal insufficiency) is the too-little picture: hypotension, hyponatremia, hyperkalemia, hypoglycemia, weight loss, fatigue, and bronze hyperpigmentation. Addisonian crisis is a shock emergency requiring fluids and intravenous corticosteroids, and steroids are never stopped abruptly. Cushing’s syndrome is the mirror image from too much cortisol: moon face, buffalo hump, truncal obesity with thin extremities, fragile skin, hyperglycemia, hypertension, hypokalemia, osteoporosis, and a blunted response to infection — infection risk is a frequent correct answer, because cortisol masks the usual signs.

SIADH vs diabetes insipidus, plus what to study next

These two are pure ADH logic, and the labs move in opposite directions.

• SIADH — too much ADH. Water is retained, so the patient is soaked inside: dilutional hyponatremia, low serum osmolality, concentrated urine, weight gain, and neurologic changes from the low sodium. Management centers on fluid restriction, daily weights, and seizure precautions.
• Diabetes insipidus — too little ADH. Water pours out, so the patient is dry inside: large volumes of dilute urine, intense thirst, hypernatremia, high serum osmolality, and real hypovolemia risk. Management means replacing fluids, monitoring intake and output closely, and giving desmopressin when ordered. Despite the name, it has nothing to do with blood glucose.

Two teaching topics round out this area. Sick-day rules: do not stop insulin simply because you are not eating, check glucose more often, stay hydrated, check ketones as directed, and call the provider for persistent vomiting. Foot care: inspect the feet daily, dry between the toes, never go barefoot, test water temperature by hand, and report any break in the skin.

The most efficient way to consolidate this is question practice rather than rereading. Work through endocrine items, read the rationale on every one — including the ones you answered correctly — and notice which hormone direction each stem is describing. That habit turns a long list of disorders into one pattern you already know how to apply.