Insulin Types and Peak Times

Rapid-acting (lispro, aspart) peaks in 1-3 hours and is given right before meals; regular insulin peaks 2-5 hours after subcutaneous injection and is the only type safe for IV push in DKA. NPH peaks 4-12 hours, creating the highest hypoglycemia risk mid-afternoon or overnight if given in the morning. Long-acting glargine and detemir have no pronounced peak and cannot be mixed with other insulins in the same syringe. NCLEX loves asking when a patient is at greatest risk for hypoglycemia based on the insulin's peak time relative to when it was administered.

Mixing and Administration Technique

When mixing regular and NPH insulin, always draw up regular (clear) first, then NPH (cloudy) — 'clear before cloudy' — to avoid contaminating the regular vial with intermediate-acting insulin. Rotate injection sites within the same anatomic region to maintain absorption consistency and prevent lipodystrophy. Never administer insulin glargine mixed with another insulin. IV insulin drips require an infusion pump and hourly glucose checks. Priority nursing actions include checking blood glucose before administration and confirming the sliding-scale order matches the current reading exactly.

Recognizing and Treating Hypoglycemia

Hypoglycemia (glucose under 70 mg/dL) presents with shakiness, diaphoresis, tachycardia, confusion, and irritability — the brain's fuel is glucose, so neuro symptoms dominate as it worsens. If the patient is alert, give 15-20g of fast-acting carbohydrate (4 oz juice, glucose tablets) and recheck in 15 minutes — the 'rule of 15.' If unconscious or unable to swallow, give IM glucagon or IV dextrose 50%. NCLEX traps include choosing a candy bar (too much fat delays absorption) instead of pure glucose.