How should a patient's insulin regimen be adjusted if they are taking prednisone at night?

Nighttime Prednisone Insulin Management

When prednisone is taken at night instead of morning, switch from NPH insulin to long-acting basal insulin (such as insulin glargine or detemir) given at bedtime, as the hyperglycemic pattern will now peak overnight and into the following day rather than during afternoon hours. 1, 2, 3

Understanding the Altered Glycemic Pattern

• Nighttime prednisone administration fundamentally changes the hyperglycemic pattern—instead of the typical afternoon/evening peak seen with morning dosing, you'll now see peak hyperglycemia overnight and extending through the morning and early afternoon 2, 3

• The pharmacokinetics remain the same: prednisone reaches peak plasma levels 4-6 hours after administration, but now this occurs in the middle of the night (around 2-6 AM if taken at bedtime) 1

• This altered timing means NPH insulin given in the morning would completely miss the hyperglycemic window, leaving patients with severe overnight and morning hyperglycemia 2, 4

Recommended Insulin Regimen

Use long-acting basal insulin (glargine or detemir) administered at the same time as the nighttime prednisone dose:

• Start with 0.3-0.5 units/kg/day of long-acting basal insulin given at bedtime 2, 4

• For patients already on insulin, increase their existing basal insulin dose by 30-50% when starting nighttime prednisone 2

• Higher doses (up to 0.5 units/kg) are needed for high-dose prednisone (>40 mg/day) 5

Monitoring Strategy

Critical monitoring times shift to capture the new hyperglycemic pattern:

• Monitor blood glucose at 3 AM or upon waking (captures peak steroid effect), before breakfast, 2 hours after breakfast, and before lunch 2

• Target range remains 100-180 mg/dL (5.6-10.0 mmol/L) 1, 5

• Do NOT rely on afternoon or evening glucose readings—these will appear falsely reassuring and miss the actual hyperglycemic peak 2

Prandial Insulin Considerations

• Add rapid-acting insulin before breakfast and lunch if basal insulin alone doesn't achieve targets, as the steroid effect will persist through midday 2, 6

• Calculate prandial doses at 1 unit per 10-15 grams of carbohydrate, adjusting based on glucose response 1

• Evening prandial insulin may not be needed or should be reduced, as the steroid effect wanes by dinner time 3, 7

Common Pitfalls with Nighttime Prednisone

• Using NPH insulin in the morning is completely ineffective for nighttime prednisone—it peaks 4-6 hours after administration (around noon), completely missing the overnight hyperglycemic surge 2, 4

• Monitoring only daytime glucose values will dramatically underestimate the severity of hyperglycemia and delay appropriate treatment 2

• Failing to increase basal insulin sufficiently—nighttime prednisone often requires 40-60% more insulin than standard dosing due to the prolonged overnight effect 2, 4

• Not reducing evening insulin when tapering steroids—this leads to nocturnal hypoglycemia as the steroid effect diminishes 4

Dose Adjustments During Steroid Taper

• Reduce basal insulin by 10-20% for each 25-50% reduction in prednisone dose 4

• Monitor for hypoglycemia during the hours that previously showed peak hyperglycemia (overnight/morning) 2, 4

• If hypoglycemia occurs without clear cause, reduce basal insulin by an additional 10-20% 4