Understanding 70/30 Insulin
70/30 insulin is a premixed formulation containing 70% intermediate-acting NPH insulin and 30% short-acting regular insulin in a single injection, providing both basal (background) and mealtime insulin coverage with just two daily injections before breakfast and dinner. 1
What's Inside the Bottle
- 70% NPH insulin: This is the intermediate-acting component that provides background insulin coverage throughout the day, similar to what your pancreas would normally release between meals 1
- 30% regular insulin: This is the short-acting component that covers the glucose rise from your meals 1
- The combination addresses both fasting and postprandial (after-meal) glucose control with a single injection 2
How to Take It
You inject 70/30 insulin twice daily: before breakfast and before dinner. 2
Dosing Distribution
- Morning dose should be higher than evening dose - typically following a 2/3 morning and 1/3 evening distribution 3
- For example, if your total daily dose is 50 units, you would take approximately 33 units before breakfast and 17 units before dinner 3
- Never use the same dose for both injections - this is a common and dangerous mistake 3, 2
Injection Timing
- Inject 30 minutes before meals because regular insulin has a slower onset than newer rapid-acting insulins 4
- This timing ensures peak insulin levels coincide with the glucose rise from your meal 4
Critical Requirements for Success
Meal timing consistency is absolutely essential with 70/30 insulin - you must eat at regular times every day to match the insulin's action and prevent dangerous low blood sugars. 3, 2
What You Must Do:
- Eat breakfast and dinner at the same times daily 2
- Maintain consistent carbohydrate amounts at each meal 2
- Never skip meals after injecting 3
- Continue taking metformin if prescribed 2
What You Must Stop:
- Discontinue sulfonylureas (like glipizide, glyburide) when using 70/30 insulin to reduce hypoglycemia risk 2
- Stop DPP-4 inhibitors (like sitagliptin) 2
- Discontinue GLP-1 agonists (like Ozempic, Trulicity) 2
Advantages of 70/30 Insulin
- Simplicity: Only 2 injections daily versus 4+ with basal-bolus regimens, which improves adherence for patients who find multiple daily injections burdensome 2
- Cost-effectiveness: Human insulin 70/30 formulations (Humulin 70/30, Novolin 70/30) are typically the least expensive insulin options available 1, 2
- Comparable effectiveness: Studies show noninferior glycemic control compared to more complex basal-bolus regimens 2
Important Limitations and Warnings
70/30 insulin is NOT appropriate if you have irregular meal times, variable eating patterns, or unpredictable schedules - the fixed ratio lacks flexibility for individualized dosing. 2
When 70/30 Should NOT Be Used:
- Never use in the hospital - it carries unacceptably high hypoglycemia risk in inpatient settings 5
- Avoid if you have irregular work schedules or meal patterns 2
- Not suitable if you need maximum flexibility in meal planning 2
Monitoring Requirements
During the first few weeks, check your blood sugar more frequently - this transition period has the highest risk for low blood sugars. 3, 2
- Monitor both fasting (before breakfast) AND after-meal glucose levels 3, 2
- Target fasting glucose: 72-126 mg/dL (4.0-7.0 mmol/L) 2
- If hypoglycemia occurs, contact your provider immediately for dose reduction 3
Common Pitfalls to Avoid
- Never mix 70/30 with any other insulin - it comes premixed and ready to use 6
- Don't inject at irregular times - this dramatically increases hypoglycemia risk 3
- Never convert from other insulins on a 1:1 basis - dosing must be recalculated and redistributed properly 3, 5
- Don't forget to roll the vial or pen gently before injecting to ensure proper mixing of the suspension 6