What is the correction scale for an adult patient with type 2 diabetes taking 45 units of NPH (Neutral Protamine Hagedorn) insulin twice daily?

Correction Scale for NPH 45 Units BID

For a patient on NPH 45 units twice daily, use a simplified correction scale with rapid-acting insulin: 2 units for glucose >250 mg/dL and 4 units for glucose >350 mg/dL, checking premeal glucose levels. 1

Recommended Correction Scale

The 2024 American Diabetes Association guidelines provide a simplified sliding scale specifically for patients on basal or intermediate-acting insulin like NPH 1:

• Premeal glucose >250 mg/dL (>13.9 mmol/L): Give 2 units of short- or rapid-acting insulin 1
• Premeal glucose >350 mg/dL (>19.4 mmol/L): Give 4 units of short- or rapid-acting insulin 1

Stop the sliding scale when it is not needed daily 1

Monitoring Strategy

• Check blood glucose before meals (before lunch and before dinner) to guide correction insulin dosing 1
• Target premeal glucose: 90-150 mg/dL (5.0-8.3 mmol/L), though this may be adjusted based on overall health and goals of care 1
• Monitor for hypoglycemia: if >2 premeal values per week are <90 mg/dL (<5.0 mmol/L), decrease medication doses 1

Alternative Correction Scales for Special Populations

For insulin-sensitive patients or those at higher risk of hypoglycemia, a more conservative correction scale may be appropriate 2:

• Blood glucose 150-200 mg/dL: 1 unit 2
• Blood glucose 201-250 mg/dL: 2 units 2
• Blood glucose 251-300 mg/dL: 3 units 2
• Blood glucose 301-350 mg/dL: 4 units 2
• Blood glucose >350 mg/dL: 5 units and notify physician 2

For steroid-induced hyperglycemia, use a more aggressive correction scale of 1 unit for every 40-50 mg/dL above target (150 mg/dL), with particular attention to afternoon and evening values when steroid effect peaks 3

Critical Safety Considerations

• Do not use rapid- or short-acting insulin at bedtime to avoid nocturnal hypoglycemia 1
• If hypoglycemia occurs (<70 mg/dL), reduce the NPH dose by 10-20% 4, 2
• The correction scale should be discontinued when not needed on a daily basis to avoid unnecessary complexity 1

NPH Dose Adjustment Algorithm

While maintaining the correction scale, adjust the underlying NPH doses based on patterns 1:

• If 50% of premeal glucose values are above goal over 2 weeks: Increase NPH dose by 2 units 1
• If >2 premeal values per week are <90 mg/dL: Decrease NPH dose by 2 units 1

This approach prioritizes safety by using a simplified, conservative correction scale that minimizes hypoglycemia risk while addressing hyperglycemia, which is particularly important for older adults or those with complex medical conditions 1.