Novolin 70/30 is a premixed insulin that combines two types of human insulin in a single vial: 70% intermediate-acting insulin (NPH) and 30% short-acting insulin (Regular). It’s designed to cover both the blood sugar spike after meals and the baseline insulin needs between meals, reducing the number of separate injections a person with diabetes needs each day.
How the Two Components Work Together
The “70/30” in the name refers to the exact ratio of the two insulins in the mix. The 30% Regular insulin component is the fast-working portion. It starts lowering blood sugar within 30 to 60 minutes after injection, handling the glucose surge that comes from eating. The 70% NPH insulin component acts more slowly, providing a longer backdrop of blood sugar control that stretches across several hours between meals.
Because these two components have different time profiles, a single injection does double duty. The Regular insulin covers the meal you’re about to eat, while the NPH insulin continues working well after that meal is digested. Peak activity for the combined mix occurs at roughly 4 hours after injection, reflecting the overlap between the fading short-acting insulin and the building intermediate-acting insulin.
When and How to Inject It
Novolin 70/30 needs to be injected about 30 minutes before a meal. This lead time gives the Regular insulin component enough time to start working so it aligns with the rise in blood sugar from food. Faster-acting analog insulins can be taken closer to mealtime, but Novolin 70/30 requires that 30-minute window because Regular insulin is inherently slower to absorb.
Because the NPH portion settles in the vial, you need to gently roll or tip the vial between your palms before drawing up a dose. The goal is a uniformly cloudy appearance. Shaking the vial too vigorously can create air bubbles or damage the insulin, so a slow rolling motion is the standard technique. If the liquid looks clumpy, frosted, or has particles stuck to the glass, the vial should be discarded.
Novolin 70/30 vs. NovoLog Mix 70/30
These two products sound nearly identical, but they contain different types of insulin. Novolin 70/30 pairs NPH with Regular human insulin, which is short-acting. NovoLog Mix 70/30 pairs an intermediate-acting insulin with a very fast-acting analog insulin that begins working in under 30 minutes and peaks at 60 to 90 minutes.
The practical difference: NovoLog Mix 70/30 can be injected closer to mealtime because its fast-acting component absorbs more quickly. Novolin 70/30’s Regular insulin needs that 30-minute head start. NovoLog Mix 70/30 also requires a prescription, while Novolin 70/30 does not in most situations (more on that below). The two are not interchangeable, and switching between them requires a dosing adjustment.
Over-the-Counter Availability and Cost
Novolin 70/30 is one of the few insulins in the United States that can be purchased without a prescription. It’s stored behind the pharmacy counter, so you won’t find it on a shelf, but you can ask a pharmacist for it directly at retailers like Walmart and CVS. Walmart sells a version under its ReliOn brand, produced by the same manufacturer (Novo Nordisk), for as little as $25 per vial.
This accessibility makes Novolin 70/30 a critical option for people who lose insurance coverage, can’t afford newer analog insulins, or need insulin in an emergency. However, “available without a prescription” doesn’t mean “use without guidance.” The dosing, timing, and blood sugar monitoring involved with any insulin carry real risks, and the over-the-counter status doesn’t change that.
Hypoglycemia and Other Risks
The most significant risk with Novolin 70/30, as with any insulin, is low blood sugar. Because the NPH component keeps working for hours, hypoglycemia can occur not just right after a meal but also between meals or overnight. Skipping a meal after injecting, exercising more than usual, or injecting too large a dose all increase the risk.
Signs of low blood sugar include shakiness, sweating, confusion, rapid heartbeat, and sudden hunger. Severe episodes can cause loss of consciousness. Keeping a fast-acting sugar source on hand (glucose tablets, juice, regular soda) is a standard safety measure for anyone using insulin.
The premixed ratio also means you can’t adjust the two components independently. If you need more mealtime coverage but not more between-meal insulin, or vice versa, a premixed product limits your flexibility. This is one reason many prescribers prefer separate long-acting and rapid-acting insulins for people whose needs vary throughout the day.
Storage Guidelines
Unopened vials should be kept in the refrigerator (36°F to 46°F). Once you start using a vial, it can stay at room temperature, between 59°F and 86°F, for up to 28 days. After 28 days at room temperature, the insulin should be thrown away regardless of how much is left. Exposure to extreme heat, direct sunlight, or freezing temperatures damages insulin and makes it unreliable, even if it looks normal in the vial.