My daughter has recently switched from NPH to Lantus. With NPH, insulin adjustment seems fairly straightforward, because we could track our daughter’s blood sugar levels and adjust either the NPH or the Humalog, depending on the timing of the high or low blood sugar trends relative to the timing of the insulin injections. Since each type of insulin had a “peak” period, it was usually clear which insulin needed to be adjusted. But with Lantus, I’m not certain I understand the basic principle behind dosing. For example, if blood sugars are running high, does this mean that the Humalog should be increased or the Lantus? Since the Lantus doesn’t really have a peak, what would need to happen in order to cause a person to adjust the Lantus dose either up or down? Perhaps the Lantus dose is determine by some sort of formula (say, based on age, size, and aggregate food intake) rather than being based on the frequent fine-tuning that we used to do with NPH? I tried to ask this question at our daughter’s clinic, but the answer was rather vague. I would like to have a clearer understanding of the basic principles and haven’t found any Internet discussion of this particular question.

I hope I can help.

I must preface by saying how impressed I am that you have recognized this. Many families do not, despite years of diabetes management, understand that different insulins have different times of onset and of peak action. The use of intermediate (NPH and Lente) and short acting insulin (Regular and Humalog or NovoLog) combinations still work very, very well. There has been a popular trend of late to switch patients onto a more physiologic way of giving insulin, using a rather peakless, baseline insulin, such as glargine (Lantus).

I think some people get switched because they need the flexibility in lifestyle in terms of meal planning and activities. If you are playing soccer at 4 p.m., it sure is problematic if your morning dose of NPH kicks in and drops your glucose down. That type of issue is less worrisome with Lantus.

The formula? None…really. But, there are tricks to make the conversion from NPH to Lantus. Commonly, people will add up the total daily dosage of NPH and take 80% of that number to give as the once daily dose of Lantus. Another approach is to estimate that 40-60% of the total daily insulin requirement in the non-diabetic individual is baseline, always-there-in-the-background insulin. Thus, a dose of insulin for the day is estimated and then give 40-60% of that number as Lantus.

For practical purposes, if you find that the fasting glucose level is consistently high, and especially so if essentially all the pre-meal glucose levels are high, that suggests that an increase in the baseline insulin is required. If you find that the pre-meal glucose level is within your target, but the value about two hours after the meal is too high (or too low for that matter), it suggests that you need to adjust your insulin-to-carbohydrate ratio of your short-acting Humalog or NovoLog. If you still use Regular for the short-acting, then different approaches may be in order.

Your diabetes team, I am sure, does not wish to sound vague. If you do not understand, or their responses still seem unclear, do not hesitate to say so! Believe me, they want you to understand on the front end as it leads to less calls after hours!

DS