What is the appropriate starting dose of NPH insulin for an 82-year-old obese (BMI 33) female patient with type 2 diabetes, who consumes a total of 220 grams of carbohydrates per day?

Starting NPH Insulin in an 82-Year-Old Female with Type 2 Diabetes on Tube Feeding

For this 82 kg patient receiving 220 grams of carbohydrates daily via tube feeding, start NPH insulin at 8-16 units once daily in the morning, using the weight-based calculation of 0.1-0.2 units/kg/day. 1

Initial Dose Calculation

• Begin with 0.1-0.2 units/kg/day based on body weight, which for an 82 kg patient equals 8-16 units daily 1
• Start at the lower end (8-10 units) given the patient's advanced age (82 years old) to minimize hypoglycemia risk, as elderly patients are at higher risk for adverse effects 1
• The degree of hyperglycemia should guide whether to use 0.1 units/kg (mild hyperglycemia) versus 0.2 units/kg (marked hyperglycemia) 1

Timing and Administration for Tube Feeding

• Administer NPH in the morning if tube feeding is continuous throughout the day 2
• Consider splitting to twice-daily dosing (2/3 morning, 1/3 evening) if the patient has persistent hyperglycemia on once-daily dosing, particularly given the substantial carbohydrate load of 220 grams daily 3
• For continuous tube feeding, NPH can be given two or three times daily to match the continuous nutrient delivery 2

Titration Strategy

• Increase the dose by 2-4 units (or 10-15%) once or twice weekly until fasting blood glucose targets are met 1
• Target fasting glucose <130 mg/dL for this elderly patient, with more relaxed targets appropriate given age and comorbidities 1
• Monitor glucose every 4-6 hours initially to assess adequacy of the regimen and identify patterns of hyper- or hypoglycemia 3

Important Considerations for This Patient

• Continue metformin if the patient is taking it, as metformin combined with insulin reduces weight gain, lowers insulin requirements, and decreases hypoglycemia risk 4
• The high BMI of 33 indicates insulin resistance, which may require doses toward the higher end of the range (0.2 units/kg) or even higher as therapy progresses 1, 5
• For elderly patients, once-daily basal insulin is associated with minimal side effects and may be reasonable given potential limitations in visual, motor, or cognitive abilities 2

Adding Prandial Coverage if Needed

• If NPH alone does not achieve glycemic targets after appropriate titration, consider adding rapid-acting insulin at 4 units per bolus or 10% of the basal dose 1, 3
• Given the tube feeding schedule, prandial insulin timing would need to align with bolus feeding times if applicable 3

Critical Pitfalls to Avoid

• Do not start with excessive doses in this elderly patient—hypoglycemia risk is substantial and potentially catastrophic at age 82 1, 2
• If hypoglycemia occurs (glucose <70 mg/dL), immediately reduce the NPH dose by 10-20% without waiting 3, 2
• Watch for overbasalization (basal dose >0.5 units/kg, high glucose variability, or hypoglycemia), which signals need for prandial rather than additional basal insulin 1
• Monitor closely if tube feeding is interrupted or discontinued, as insulin requirements will drop precipitously and the NPH dose must be reduced accordingly 2