Regular insulin

HUMULIN R

What it isShort-acting insulin-receptor agonist; mealtime diabetes treatment, DKA infusion, and hyperkalemia.

Why this oneIt is the standard insulin for intravenous treatment of diabetic ketoacidosis and hyperkalemia.

What limits itIts slower subcutaneous onset requires meal planning that rapid analogues avoid. Hypoglycemia is the limiting toxicity.

FDA-approved for

FDA dosing	Population	Start	Target	Max
Diabetes mellitus — glycemic control	adult	Individualized; SC inj ~30 min before meals	Individualized to metabolic needs, glucose monitoring, and glycemic goal	Individualized
Diabetes mellitus — glycemic control	pediatric	Individualized; SC inj ~30 min before meals	Individualized with frequent glucose monitoring	Individualized

Renal Not studied; increased hypoglycemia risk — may require more frequent dose adjustment and glucose monitoring

Hepatic Not studied; increased hypoglycemia risk — may require more frequent dose adjustment and glucose monitoring

Increase glucose-monitoring frequency during any insulin regimen change

Inject SC ~30 min before meals into thigh, upper arm, abdomen, or buttocks; rotate sites (lipodystrophy/cutaneous amyloidosis risk); do not inject into affected areas
SC regimens generally combined with an intermediate- or long-acting insulin
IV only under medical supervision: 0.1-1 unit/mL in 0.9% NaCl; monitor glucose and potassium
Do not mix with insulin preparations other than Humulin N
Inspect before use: must be clear and colorless
Dose adjustments may be needed with changes in activity, meal pattern, renal/hepatic function, or acute illness

Never share needles or syringes (blood-borne pathogen risk)
Regimen changes (strength, manufacturer, type, injection site/method) can cause hypo- or hyperglycemia — change under close supervision with increased glucose monitoring
Hypoglycemia — most common adverse reaction; may be life-threatening; impairs driving/machine use
Medication errors — accidental mix-ups between insulin products; check label before injection
Hypersensitivity — severe generalized allergy incl. anaphylaxis can occur
Hypokalemia — may be life-threatening; monitor potassium in at-risk patients (esp. IV use)
Fluid retention and heart failure with concomitant thiazolidinediones — observe; consider TZD dose reduction/discontinuation

Pregnancy Decades of data show no association with major birth defects/miscarriage; poorly controlled diabetes itself carries maternal/fetal risk

Lactation Transferred into human milk; no adverse reactions reported in breastfed infants; weigh benefits

NO BOXED WARNINGS

Principal riskHypoglycemia

Cost, est. cash$35–$650/month

Generic entryLong generic

Therapeutic safety burden3 / 4

Overdose danger4 / 4

Weight-gain liability3 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk0 / 4

Legacy pregnancy categoryMultiple / indication-, trimester- or formulation-dependent

Defining liabilityHypoglycemia can rapidly cause seizures, coma or death; dosing and meal mismatches are the principal hazard.