Establishing a Baseline

To Peak or Not to Peak

| Jun 1, 2004

Since Lantus first appeared on the market in 2001, it has been praised as the best basal insulin for good blood glucose control, primarily because it has a flat, peakless action. It fills a need for people who desire consistent insulin action around the clock, but like other basal insulins, it has to be set, tested and adjusted to match the user’s need.

On the other hand, there are still people whose needs are best met by a peaking basal insulin. NPH and Lente are intermediate insulins that have been available for 50 years. Their peaking activity can be a blessing for the right user.

Tips for Peakless Action With Lantus

Lantus begins working earlier, at one to two hours, and has an almost peakless profile that lasts 18 to 26 hours in most users. Consequently, one injection a day is often all that’s needed. The injection can be taken at any time of day, but it is important to take it at the same time each day to avoid creating a gap in action or a doubling of action resulting when a dose is taken earlier or later than usual.

People who experience less than 24 hours of action from their Lantus may find that blood glucose readings taken at the time of the injection tend to vary from day to day as a result of a gap in coverage. For instance, if Lantus is taken once a day at bedtime, the bedtime blood glucose will tend to vary in those who experience a shorter action time.

In those for whom Lantus works less than for 24 hours, it often has a slight peak in its activity about six hours after the injection. This can cause a low blood glucose six to eight hours following an injection, which can result in night lows when Lantus is taken at bedtime. Often those who experience a shorter action time with Lantus find that the situation can be improved by splitting the dose in half and taking these new doses twice a day, approximately 12 hours apart. About one-third of users find their results are improved when they do this. Splitting the dose also has the advantage that doses do not need to be taken at exactly the same time each day.

Cautions About Lantus

  • Lantus is a clear insulin. It cannot be mixed with other insulins. It should not even be drawn into a syringe that has held another insulin. If it appears cloudy, it has likely come in contact with another insulin and should be discarded.
  • Although the Lantus bottle is taller and narrower, it may be confused with other clear insulins like Humalog or NovoLog. Occasionally, users have mistakenly taken a large dose of rapid insulin at bedtime instead of their usual Lantus. Wrap a rubber band around the Lantus bottle to help avoid confusion.
  • As background (basal) insulin coverage, Lantus should be taken every day, even during an illness.
  • Lantus is mildly acidic compared to other insulins. About one out of every 40 users, often someone who requires large doses, may notice slight discomfort at the injection site.

NPH and Lente—When You Want a Peak

Some people do not want a completely flat profile from their basal insulin. They may prefer to have an insulin with a peak that they can harness to meet a specific need. Often these people use NPH, which has a significant peak four to six hours after an injection, with activity that lasts 14 to 20 hours. NPH tends to peak earlier and taper off faster than Lente, while Lente has a flatter peak and a longer period of action.

One use of this peak is to give an injection of NPH with Humalog or NovoLog rapid-acting insulin at breakfast. Humalog or NovoLog covers the breakfast carbohydrates, and the NPH peak can cover the carbs eaten at lunch. This eliminates the need for an injection at lunch.

Another use for NPH’s peak is a bedtime injection of NPH to cover the rising need for insulin during the night associated with a Dawn Phenomenon (pattern of early morning rise in blood glucose levels). However, because the timing of its peak can be inconsistent, this approach may generate control problems rather than solve them.

NPH has a shorter action time than Lantus—often about 14 hours—and its activity can tail off after 10 hours. This can cause distinct gaps in action when only two doses a day are used. If this gap occurs at a mealtime, it can be covered by taking more Humalog or NovoLog than usual for the carbs in that meal. However, a more reliable method is to divide the dose of NPH into three injections through the day.

In the case of cloudy insulins like NPH and Lente, many users do not mix the insulin well before use (at least 20 rolls and shakes of the bottle are recommended), and several studies have found variable insulin effect from day to day due to improper mixing. Be sure to mix any cloudy insulin well prior to each use.

For more information on this topic, see “Using Insulin” at or call (800) 988-4772.

In addition to “Using Insulin,” John Walsh, PA, CDE, and Ruth Roberts, MA, are also the authors of “Pumping Insulin” (1st, 2nd and 3rd editions). All of these books can be purchased at the Diabetes Mall at

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Posted by Anonymous on 19 January 2008

We had a lot of trouble with Lantus peaking and causing severe lows. We're using Levemir now and it actually seems to be relatively flat over 24 hours.

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