From the Guidelines
For a 56-year-old male with an HbA1c of 10.6% on metformin 1000 mg twice daily and glipizide 60 mg twice daily who is unable to be approved for long-acting insulin, I recommend starting NPH insulin at 10 units per day or 0.1-0.2 units/kg per day, as suggested by the 2025 standards of care in diabetes 1. The patient's current oral medication regimen should be continued, with consideration for adjusting the glipizide dose to minimize the risk of hypoglycemia when initiating insulin therapy.
- Key considerations for NPH insulin initiation include:
- Setting a fasting plasma glucose (FPG) goal, as outlined in the standards of care 1
- Choosing an evidence-based titration algorithm, such as increasing the dose by 2 units every 3 days to reach the FPG goal without causing hypoglycemia 1
- Monitoring for hypoglycemia and adjusting the dose accordingly, with a reduction of 10-20% if hypoglycemia occurs without a clear reason 1
- The patient should be educated on the importance of monitoring blood glucose levels, recognizing hypoglycemia symptoms, and managing hypoglycemia effectively.
- Regular follow-up appointments, ideally every 2-4 weeks, are crucial to assess the adequacy of the insulin dose and make adjustments as needed to achieve optimal glycemic control, as recommended by the 2025 standards of care in diabetes 1.
From the Research
Recommended NPH Dose
To determine the recommended NPH dose for a 56-year-old male with an HbA1c level of 10.6% on metformin 1000 mg twice daily and glipizide 60 mg twice daily, we need to consider the available evidence.
- The study 2 compared morning versus bedtime administration of NPH insulin in 12 subjects with Type 2 diabetes and found that mean daily total insulin dosage was equivalent for both morning and bedtime administration schedules, with a mean daily total insulin dosage of 0.36 +/- 0.03 units kg-1 for morning administration and 0.37 +/- 0.03 units kg-1 for bedtime administration.
- Another study 3 compared the effect of morning and bedtime NPH insulin combined with daytime sulfonylurea on glycemic control in NIDDM patients and found that the dose of NPH insulin was 22 +/- 1 IU, which is approximately 0.3-0.4 units kg-1 per day for a 70 kg person.
- A study 4 examined the safety and efficacy of normalizing fasting glucose with bedtime NPH insulin alone in NIDDM and found that the insulin dose was 80 +/- 9 U/day, which is approximately 0.86 +/- 0.10 U/kg per day for a 93 kg person.
Calculation of Recommended NPH Dose
Based on the available evidence, the recommended NPH dose for a 56-year-old male with an HbA1c level of 10.6% on metformin 1000 mg twice daily and glipizide 60 mg twice daily can be estimated as follows:
- Assuming a weight of 70-90 kg, the recommended NPH dose would be approximately 0.3-0.4 units kg-1 per day, which is equivalent to 21-36 units per day for a 70 kg person or 27-36 units per day for a 90 kg person, based on the study 3.
- Alternatively, assuming a weight of 93 kg, the recommended NPH dose would be approximately 0.86 +/- 0.10 U/kg per day, which is equivalent to 80 +/- 9 U/day, based on the study 4.
Timing of NPH Administration
The timing of NPH administration is also an important consideration.
- The study 2 found that bedtime administration of NPH insulin resulted in improved basal glycaemia and overall metabolic control compared to morning administration.
- The study 3 found that bedtime NPH insulin resulted in lower morning blood glucose levels, while morning NPH insulin resulted in lower evening blood glucose levels.
- The study 4 found that bedtime NPH insulin alone was effective in normalizing fasting glucose levels and improving glycemic control in NIDDM patients.
Overall, the recommended NPH dose for a 56-year-old male with an HbA1c level of 10.6% on metformin 1000 mg twice daily and glipizide 60 mg twice daily is approximately 20-40 units per day, administered at bedtime 2, 3, 4. However, the exact dose and timing of administration should be individualized based on the patient's specific needs and response to treatment.