October 14, 2003
Question from Pennsylvania, USA:
What is an appropriate sliding scale ratio for a 13 year old athletic child? I was informed that one unit of Humalog will bring the blood sugar down 50 mg/dl [2.8 mmol/L] and that 1 unit of insulin will cover about 10-15 grams. Does this sound accurate?
I am not a big fan of “sliding scales” as they often lead to “chasing of blood sugars”: chase it down, goes too far, give food, goes too high, give insulin, chase it down, etc. Extra insulin in this way often is not accounting for the effects of the NPH given earlier. Blood sugars can really rollercoaster around this way.
For a starting point, I’d consider 1 unit of Humalog insulin to bring down the glucose by 50 mg/dl [2.8 mmol/L], but some people require a bit more or some less. Puberty and its hormones are antagonistic to insulin thus requiring more insulin. Perhaps 1 unit of Humalog may only bring your son down 25 mg/dl [1.4mmol/L]. Of course, activity enhances the effect of insulin.
For people on basal/bolus insulin and who give insulin based on food intake, a good starting point is 1 unit for every 15 grams of carbohydrates consumed. Some people require more or less, or different ratios for different meals or different types of meals. The carbs in 15 grams of orange juice are absorbed differently than the 15 grams carbs in a small slice of pizza, for example. Often people require more insulin at breakfast, relative to other meals.