Insulin 70/30: what it treats, how to take it, side effects
Last updated September 3, 2026.
Insulin 70/30 is a premixed human insulin: 70% intermediate-acting NPH insulin and 30% short-acting regular insulin in one injection. It covers both a meal and the hours after it, and it is sold as Novolin 70/30 and Humulin 70/30.
What does it treat?
Insulin 70/30 improves blood sugar control in adults and children with diabetes mellitus. The regular component handles the glucose rise from the meal that follows the injection, while the NPH component keeps working between meals and overnight. It suits people whose eating schedule is regular, because the mix is fixed and cannot be adjusted separately.
How do you take it?
Inject insulin 70/30 under the skin of the abdomen, thigh, upper arm, or buttocks about 30 minutes before a meal, and rotate sites to avoid skin changes. It is typically dosed twice daily, with each dose intended to cover two meals or a meal and a snack. The liquid should look cloudy after you gently roll the vial or pen to mix it; do not use it if it stays clear or has clumps. Never mix 70/30 in a syringe with other insulins, and never share a pen or syringe. A FlexPen in use is kept at room temperature below 86°F and discarded after 28 days; it should not go back in the refrigerator once in use. If you miss a dose, check your glucose and follow your care team's plan; never double the next dose.
Side effects to know
- Common: low blood sugar (shakiness, sweating, hunger, fast heartbeat, confusion), injection site reactions, skin thickening or dents at heavily used sites, and weight gain.
- Serious: severe hypoglycemia requiring another person's help, low potassium (cramps, weakness, irregular heartbeat), and allergic reactions with rash, swelling, or breathing trouble.
Who should not take it?
Do not use insulin 70/30 during an episode of low blood sugar, or if you have a known allergy to any of its ingredients. Because the ratio is fixed, it is a poor fit for people with unpredictable meal times or big swings in daily activity; that is a conversation for your prescriber, not something to adjust on your own. Alcohol and many common medicines change insulin needs. Human insulin has a long record of use in pregnancy, but doses need close medical adjustment throughout.
When is it an emergency?
Call 911 if a person on insulin cannot be woken, has a seizure, or is too confused to swallow; give glucagon if you have it and stay with them. Signs of a severe allergic reaction, including swelling of the face, lips, or throat, trouble breathing, or a spreading rash, also mean call 911. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
What does the 70/30 mean?
The numbers describe the mix: 70% NPH insulin, which works at an intermediate pace, and 30% regular insulin, which works quickly after the injection. The ratio is fixed, so the two parts cannot be adjusted separately the way they could with two separate insulins.
Why is my 70/30 insulin cloudy?
The NPH component makes the liquid milky. Gently roll the vial or pen until it looks uniformly cloudy before every injection. Do not use it if it stays clear after mixing, has particles or clumps, or looks frosted.
How many times a day do you take insulin 70/30?
The label describes typical dosing as twice daily, injected about 30 minutes before a meal, with each dose covering two meals or a meal and a snack. Your own schedule and dose are set from your glucose readings.
Can I mix 70/30 with another insulin in the same syringe?
No. Premixed 70/30 insulin should not be combined in a syringe with other insulin products. If your regimen needs a different ratio, your prescriber changes the product or the plan rather than mixing.
How do I store the pen?
An unopened pen stays in the refrigerator. Once in use, a FlexPen is kept at room temperature below 86°F, not back in the refrigerator, and thrown out after 28 days even if insulin remains. Never freeze insulin or use insulin that has been frozen.
Does insulin 70/30 cause weight gain?
Weight gain is a known effect of insulin therapy. If it becomes a problem, your care team can revisit the dose, meal plan, and activity together rather than having you cut doses on your own, which raises the risk of highs.