How much sliding scale insulin should I give?

The American Diabetes Association goals for inpatient management of diabetes can be found here. The goal fingerstick for non-critically ill patients is 140-180 mg/dL. Even though we don’t always do it (read: rarely do it), it is ideal to calculate a patient’s inpatient insulin regimen based on body weight. Sliding scales should not be the sole form of insulin administration as there is actually no evidence to support their use!

Sliding scale insulin is extra coverage and usually consists of short-acting insulin like lispro (Humalog) or insulin aspart (Novolog). These forms of insulin start working in 15-60 minues and peak in 1-3 hours.

Short-acting insulin vs. regular insulin for a sliding scale? Studies have found that there is no significant difference in outcomes, but generally regular insulin should be used for patients who are NPO, on TPN or continuous tube feeds.

To create an insulin sliding scale, calculate your patient’s “insulin sensitivity factor.”

ISF = 1700/total daily dose of insulin

For example: if someone takes 20 U insulin glargine (Lantus) and 2 U insulin lispro (Humalog) with meals, their total daily dose of insulin is 20 + 2*3= 26. 1700/26=65, so 1 U Humalog for sliding scale would be expected to lower their fingerstick glucose by 65.

The University of Pittsburgh put out a patient safety study with a preset protocol for low, moderate, and high-risk patient sliding scales that can be found here.

Important note: bedtime or “QHS” sliding scales should, generally speaking, be more gentle than mealtime sliding scales, as there is a risk for overnight hypoglycemia.

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