From the Guidelines
NPH insulin should be administered twice daily, with 2/3 of the total dose given before breakfast and 1/3 given at bedtime, as this regimen has been shown to provide optimal glycemic control and minimize the risk of hypoglycemia 1. The administration of NPH insulin is crucial for maintaining stable blood glucose levels throughout the day and night.
- The morning dose helps to control blood glucose levels during the day, while the evening dose helps to control overnight glucose levels.
- The pharmacokinetic profile of NPH insulin, which begins working within 1-2 hours after injection, peaks in 4-8 hours, and lasts approximately 12-18 hours, supports this dosing regimen 1.
- A twice-daily regimen with a morning and bedtime dose allows for more flexible dosing and can help to improve glycemic control, as recommended by recent guidelines 1.
- It is essential to individualize the dosing regimen based on the patient's specific needs and current glycemic control, and to consider converting to a twice-daily NPH regimen if the patient is currently on a bedtime NPH regimen 1.
From the Research
Administration Time of NPH Insulin
The optimal time for administering NPH (Neutral Protamine Hagedorn) insulin is a topic of interest for managing diabetes effectively. Studies have compared the effects of administering NPH insulin at different times of the day to determine the best approach for glycemic control.
Comparison of Morning vs. Bedtime Administration
- A study from 1992 2 compared morning versus bedtime administration of NPH insulin in 12 subjects with Type 2 diabetes. The results showed that bedtime administration of NPH insulin resulted in improved basal glycaemia and overall metabolic control compared to morning administration.
- Another study from 1998 3 found that adjusting the evening insulin dose, including the use of NPH insulin at bedtime, could improve evening blood glucose control without worsening nighttime glucose levels.
Effects on Glycemic Control
- Research from 1991 4 explored the use of human ultralente insulin before supper and NPH insulin before breakfast in children and adolescents with IDDM. Although this study did not directly compare morning and bedtime NPH administration, it highlighted the importance of optimizing insulin regimens for better glycemic control.
- A 2008 study 5 compared the nocturnal glucose metabolism after bedtime injection of insulin glargine or NPH insulin in patients with type 2 diabetes. It found that NPH insulin had a greater effect on glucose disappearance and endogenous production during the night, while insulin glargine was more effective in the morning.
Insulin Kinetics and Glycemic Control
- A 1997 study 6 investigated the nighttime insulin kinetics and glycemic control in type 1 diabetes patients following administration of an intermediate-acting lispro preparation (NPL) compared to NPH insulin. The study found that NPH and NPL were equally effective in controlling overnight glycemia.
Timing Considerations
Based on the available evidence, administering NPH insulin at bedtime appears to offer benefits for glycemic control, particularly in reducing fasting hyperglycemia and improving overall metabolic control 2, 3, 5. However, the optimal timing may depend on individual patient factors and the specific insulin regimen being used.