NCLEX-RN cheat sheet · Endocrine
Diabetes and insulin
Types, tests, insulin timing, lows and sick days
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Diabetes means persistently high blood glucose, from too little insulin, resistance to it, or both. The nurse's most urgent job is spotting a low before it becomes a crisis.
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At a glance
Type 1 or type 2
| Type 1 | Type 2 | |
|---|---|---|
| What happens | Immune system destroys the insulin-making cells: no insulin | Body resists insulin, or makes too little |
| Risks | Autoimmune; genetics; viruses | Age over 45, family history, obesity, metabolic syndrome, inactivity |
| Treatment | Always needs insulin | Lifestyle and drugs; some clients need insulin too |
Gestational: Usually resolves after birth, but raises the later risk of type 2.
Diagnosis
| Test | What it means |
|---|---|
| Fasting glucose | 126 mg/dL or more, after an 8-hour fast and confirmed by a second abnormal test, is diabetes |
| Unequivocal hyperglycemia | One test is enough |
| A1C | Average glucose over the past 2 to 3 months |
| Random glucose | Over 200 mg/dL suggests diabetes |
| Tolerance test | Glucose checked after a fasting 75-gram drink |
| C-peptide | Marker of the body's own insulin; helps tell type 1 from type 2 |
Insulin timing (approximate: products differ, so check the label)
| Insulin | When to give | Peak and length | Rules |
|---|---|---|---|
| Rapid: lispro (Humalog), aspart | Product-specific. Lispro: within 15 min before a meal, or right after. Aspart: 5 to 10 min before | Lispro peaks in about 1 to 3 h | The food must be there. No tray yet? Wait |
| Short: regular | About 30 min before a meal | Peaks about 3 h; lasts about 8 h | The usual IV infusion insulin |
| Intermediate: NPH | Once or twice a day | Peaks around 6 h; lasts up to a day | Cloudy: roll gently to mix. Never IV |
| Long: glargine | Once a day, same time | No real peak; lasts about 24 h | Never mix or dilute. Never IV |
| Premixed (like 70/30) | Usually twice a day, before meals | NPH plus a faster insulin | Only under the skin |
Watch: Lows are most likely near an insulin's peak. All insulin moves potassium into the cells, so watch for low potassium. IV use is product-specific (regular, certain lispro products) and closely monitored.
Hypoglycemia: the numbers and the signs
- Below 70 mg/dL is hypoglycemia. Level 2 is below 54 mg/dL.
- Level 3 (severe) means the client needs another person's help, at any glucose.
- Early: shaky, sweaty, hungry, fast heart rate, anxious. Then confused, weak, dizzy, blurred vision.
- Untreated, it can cause seizures, coma and death.
- Causes: too much insulin or a sulfonylurea, extra exercise, late or missed meals, alcohol.
- Hidden lows: older adults and clients on beta blockers. Some clients get no warning signs at all.
Treating a low
| Client | Do this |
|---|---|
| Awake, can swallow | 15-15 rule: 15 g fast carbohydrate (half a cup of juice or regular soda, or 3 to 4 glucose tablets). Recheck in 15 min; repeat until at least 70 mg/dL |
| Back in range | Meal or snack with complex carbohydrate and protein; notify the provider. No chocolate: fat slows the sugar |
| Can't swallow, unconscious or seizing | Urgent: call for help, check the airway, nothing by mouth. Glucagon (nasal or injection) or IV dextrose, concentration per protocol |
| No response after 15 min | A second glucagon dose from a new device may be given; food once able to swallow |
| After any low | Recheck repeatedly; monitor by risk, longer on sulfonylureas; report it so the plan is reassessed |
Sick days
- Illness can raise glucose, even when the client eats less.
- Check glucose at least every 4 h. Adjust insulin as the provider instructs.
- Call if glucose is over 240 mg/dL.
- Fluids: sip every 15 min if needed. Simple carbohydrates if eating is hard.
- Clients at risk check ketones every 4 to 6 hours, or as their plan directs. Call right away if ketones are present.
- Seek emergency care for trouble breathing, vomiting or severe diarrhea over 6 hours, or not keeping liquids down for 4 hours. Also seek care for a fever over 101°F for a day.
Other diabetes drugs
| Drug | Key points |
|---|---|
| Metformin | Usual first drug for type 2; with meals; alone, doesn't cause lows. Boxed warning: lactic acidosis. May be stopped before contrast imaging; not used with severe kidney disease |
| Sulfonylureas | Pancreas releases more insulin, so they can cause lows. Timing varies by drug: glimepiride with breakfast |
| Empagliflozin | Sugar leaves in the urine: watch for genital and urinary infections, dehydration, ketoacidosis. Held at least 3 days before surgery, when possible |
| Semaglutide | A GLP-1 agonist: slows stomach emptying and curbs appetite. Weekly injection or daily tablet. Boxed warning: thyroid tumors, so report a neck lump, trouble swallowing or hoarseness |
Priority and safety calls
- ★ Sudden change in mood or behavior in a client with diabetes: check the glucose now.
- ★ Can't swallow safely? No juice, nothing by mouth. Glucagon or IV dextrose per protocol, and activate the emergency response.
- Before every insulin dose: confirm why it's ordered, check the latest glucose, assess for signs of a low.
- Don't dose from a glucose someone tells you out loud: check the record. Time mealtime insulin with the tray.
- One pen, one client, even with a new needle. Hold the needle in for that pen's count: 5 for Humalog KwikPen, 10 for Lantus SoloStar.
- IV insulin runs under close supervision, with frequent glucose and potassium checks; the rate follows the protocol.
- Feet: inspect every day, between the toes too; proper footwear, never barefoot. In facilities, only podiatrists or trained staff trim toenails.
- Teach with a return demonstration: have the client show you their injection technique.
How the NCLEX tests it
- Hypoglycemia is a glucose below 70 mg/dL; level 2 is below 54 mg/dL.
- 15-15 rule: 15 g fast sugar, recheck in 15 min, only if awake and able to swallow.
- Diabetes: fasting glucose 126 mg/dL or more after an 8-hour fast, confirmed by a second abnormal test; one test is enough if hyperglycemia is unequivocal.
- Beta blockers and older age can hide the warning signs of a low.
- Sick days: check glucose every 4 h, call if over 240 mg/dL, and don't stop insulin without guidance.
- Glargine has no real peak and is never mixed; regular insulin is the usual IV insulin.
- Metformin: lactic acidosis is the boxed warning; it may be stopped before contrast imaging.
Practice it next
This sheet comes from Diabetes mellitus and hypoglycemia and Endocrine drugs in our NCLEX-RN course. Try free practice questions, or see the lessons it was written from.
Quick self-quiz
- Hypoglycemia is a blood glucose below ___ mg/dL.
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70 - An awake client who can swallow gets ___ grams of fast carbohydrate, then a recheck in 15 minutes.
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15 - Regular insulin is given about ___ minutes before a meal.
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30 - The long-acting insulin with no real peak that is never mixed is ___.
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glargine - On a sick day, the client calls if glucose is over ___ mg/dL.
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240 - A client who can't swallow needs glucagon or IV ___, per protocol.
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dextrose - At school, a Section ___ plan describes how the student gets the care they need.
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504
Sources
- Open RN, Nursing: Health Alterations, 7.5 Diabetes Mellitus
- Open RN, Nursing Pharmacology 2e, 9.4 Antidiabetics
- American Diabetes Association, Standards of Care in Diabetes, section 6: glycemic goals and hypoglycemia (2026)
- DailyMed, Humalog (insulin lispro) label
- DailyMed, Lantus (insulin glargine) label
- DailyMed, metformin hydrochloride tablets label
- NIDDK, Helping the Student with Diabetes Succeed: A Guide for School Personnel (reviewed May 2020)
More endocrine cheat sheets
Educational use only. This sheet is a study aid for the NCLEX-RN, not a substitute for clinical judgment, your facility’s policy or the provider’s orders. Where practice varies, follow facility policy and state law. NCLEX® and NCLEX-RN® are registered trademarks of NCSBN, which does not endorse these materials.