I have a question regarding insulin to carbohydrate (I:C) ratios. My daughter currently takes nine units of Lantus in the evening and her I:C ratio is 1:25. We’ve increased her Lantus within the last few months, but her I:C has stayed the same. While the Lantus provides a little bit of a lower blood sugar than previously, she is still pretty high. Here are her numbers for the last week. She does four tests a day, breakfast, lunch, dinner and before bed.

Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7

213 mg/dl[11.8 mmol/L]
279 mg/dl[15.5 mmol/L]
220 mg/dl[12.2 mmol/L]
189 mg/dl[10.5 mmol/L]
139 mg/dl[7.7 mmol/L]
204 mg/dl[11.3 mmol/L]
142 mg/dl[7.9 mmol/L]

276 mg/dl[15.3 mmol/L]
213 mg/dl[11.8 mmol/L]
144 mg/dl[8.0 mmol/L]
279 mg/dl[15.5 mmol/L]
256 mg/dl[14.2 mmol/L]
270 mg/dl[15.0 mmol/L]
246 mg/dl[13.7 mmol/L]

76 mg/dl[4.2 mmol/L]
198 mg/dl[11.0 mmol/L]
131 mg/dl[7.3 mmol/L]
195 mg/dl[10.8 mmol/L]
254 mg/dl[14.1 mmol/L]
230 mg/dl[12.8 mmol/L]
271 mg/dl[15.1 mmol/L]

206 mg/dl[11.4 mmol/L]
168 mg/dl[9.3 mmol/L]
259 mg/dl[14.4 mmol/L]
255 mg/dl[14.2 mmol/L]
103 mg/dl[5.7mmol/L]
234 mg/dl[13.0 mmol/L]
95 mg/dl[5.3 mmol/L]

The doctor told us to have her try to eat between 62 and 75 grams of carbohydrates at each meal. For corrections, for anything over 151 mg/dl [8.4 mmol/L] to 225 mg/dl [12.5 mmol/L] we add one unit; for blood sugars 226 mg/dl [12.6 mmol/L] to 300 mg/dl [16.7 mmol/L], we add two units, and so forth. What would you recommend we do? Should we change her Lantus or change her I:C ratio? We’ve e-mailed our doctor and are awaiting his opinion. We are just looking for a second opinion and will, of course,follow directly what our doctor recommends.

In broad terms, looking only at the data provided (and not knowing your child, her age, her activities and her weight, etc.), I’d say that the basal dose of Lantus needs to be increased. Does she get it with the evening meal or closer to 9 to 10 p.m.?

She might need several adjustments. To get a better feel for your insulin-to-carbohydrate ratio, it might be helpful to perform some two-hour after meal checks to assess the adequacy of her ratio of 1:25. I’d like to see the two hour after meal values within 50 mg/dl of the pre-meal values, to be able to say that the I:C ratio is adequate.

How often do you use your correction? It seems that you are essentially using a “sliding scale.” You might be able to “tighten” that up a little bit, using a very similar formula: Glucose value minus the target glucose you desire and then divide this difference by a “sensitivity factor.”

For example purposes only, using your “sliding scale” you noted above, it looks like you give NO extra insulin for glucoses less than 151 mg/dl. This means you have been given a TARGET glucose of 151. I think, depending on your child’s age, etc., that this target is too loose/high! And, then, you are giving insulin for differences of about 74 (which is your “sensitivity factor”). Is it your genuine observation that a single unit of insulin brings her values down by about 74mg/dl? Again, this could be, but depending on other factors and information, I’d be a little surprised that she would be so “sensitive” to insulin.

So, after conferring with your regular doctor, you might want to consider using something like this:

Target glucose = 120 mg/dl [6.7 mmol/L]; Sensitivity Factor = 50 mg/dl [2.8 mmol/L].

So, let’s say that her glucose was 327 mg/dl [18.2 mmol/L]. The amount of additional insulin to give would calculate to: (327 – 120) divided by 50. Or, 207 divided by 50 which is 4.1 units. So, you’d give four units. This can be done concurrently with the bolus dose with the meal or essentially anytime (depending again on individual parameters). You can typically “round off” to the nearest one-half unit.

I hope this helps. Again, make no changes without conferring with your doctor.

DS