by John Walsh, PA, CDE and Ruth Roberts, MA
(Editor's Note: The authors mention many texts in this article -- and all are either pages on their website, or publications available for purchase at The Diabetes Mall. Reprinted with permission.)
See also Can Humalog Handle The Heat? and Users' Reports
Humalog is a fast-acting insulin that gives users greater flexibility and better blood sugar control. Produced by Lilly and released in 1996, this insulin offers a quicker action time than the original Regular insulin, developed in 1921. With its higher peak activity and shorter working time, users report that their eating can be more spontaneous, their control is improved and they feel better.
Although Lilly has not applied for FDA approval to use Humalog in insulin pumps, the majority of pumpers in the U.S. have already switched and appear to be very satisfied. Novo-Nordisk is planning the release of their fast-acting Novolog or aspart insulin into the U.S. market following the anticipated FDA approval late in 1999. They may also seek FDA approval for pump use for Novolog.
Like Regular, Humalog is used to cover meals and snacks. Most meals create a rise in the blood sugar for only a short period, normally two to three hours for most foods. Regular insulin takes 30 minutes to begin working, does not peak until three to four hours after the injection, and continues to lower blood sugars for six to as much as eight hours. Humalog, on the other hand, begins working in 10 minutes, peaks at one to two hours and is gone in about 3 and 1/2 hours.
The great advantage of Humalog is that it can be taken as you begin eating, rather than 30 to 45 minutes earlier, required of Regular, because it matches the "action time" for most meals. For mothers of small children and for those on the go, this is a tremendous advantage. Rather than having to anticipate when the next meal might begin, those who aren't sure when the next meal might begin and those feeling ill can simply wait to bolus as they begin eating. Kids who are picky eaters can be given a bolus after they actually finish the meal with little loss of control.
Humalog simply matches meals better, lowering the blood sugar at the same time the food is raising it. Blood sugars at one to two hours after eating do not spike as they often do with Regular, and by the end of the second hour the blood sugar is often close to its starting point. This shorter action time gives Humalog a cleaner action pattern meaning the action of the last meal bolus is gone before the next meal begins.
More important for many, there is no residual bolus activity before going to bed and fewer nighttime reactions. Humalog leaves your body more quickly so you don't have residual insulin causing low blood sugars in the late afternoon or in the middle of the night. With Humalog you're better equipped to stop blood sugars spiking between meals, and you're no longer exposed to the overlapping build-up of Regular boluses.
Humalog's clearly defined action time makes it easier to troubleshoot problems. For information on how to determine the number of carbs covered by each unit of Humalog, see the 500 Rule in the POCKET PANCREAS. Humalog is also excellent for lowering high blood sugars. Its faster action means that less time is spent at high blood sugar levels, and less residual insulin is left to trigger low blood sugars later. For information on how to safely lower highs, see the 1800 Rule, also in the POCKET PANCREAS.
These rules work when someone has their basals and boluses set up correctly and has tested their doses to make sure their total daily insulin dose is correct.
Test often. Test your blood sugar often to determine how Humalog works best for you. As you start using Humalog, it is wise to test before eating, two hours after eating, and any time you experience unusual symptoms. Test often and use special caution when lowering high blood sugars.
Covers food differently. The great advantage of Humalog is its convenience. Although a 10 to 20 minute lead time is ideal, boluses can be taken with the first bite of food with very good post-meal control. Of course, its quick action means that you must not delay eating! If the pre- meal blood sugar is high and eating is delayed to allow the blood sugar to drop, the food must be eaten at the time planned to avoid a low blood sugar.
Foods with a high glycemic index that raise the blood sugar quickly, like cold cereals or a scone for breakfast, are easier to cover with Humalog. However, low glycemic carbohydrates like pasta al dente or a bean burrito which digest more slowly can present some problems, such as hypoglycemia occurring before these foods completely digest. For these rare foods with a low GI, the bolus may be split. Take half before the meal and the second half an hour or two after eating, or use a square wave bolus or raise the basal rate temporarily. Another option is to give an injection of Regular to better match these slow carbohydrates.
|
Total Daily Insulin Dose
Covered by One Unit of Humalog
|
Approximate Grams of Carb
|
|
20
|
25
|
|
25
|
20
|
|
30
|
17
|
|
35
|
14
|
|
40
|
13
|
|
50
|
10
|
|
60
|
8
|
|
Total Daily Insulin Dose
|
Estimated Point Drop per
Unit of Humalog
|
|
20
|
90 mg/dl
|
|
25
|
72 mg/dl
|
|
30
|
60 mg/dl
|
|
35
|
51 mg/dl
|
|
40
|
45 mg/dl
|
|
50
|
36 mg/dl
|
|
60
|
30 mg/dl
|
|
75
|
24 mg/dl
|
|
100
|
18 mg/dl
|
Meals with a high fat content may also occasionally be best covered by taking a split dose of Humalog, or taking the whole dose after the meal is eaten to better match the slow digestion of these meals. And, of course, if your blood sugar is low or on the edge of low at mealtime, eat the meal and then take your bolus afterwards.
Treat lows differently. Because of Humalog's fast action, fast carbs are recommended when you need to treat a low blood sugar. Glucose tabs, honey, or candies with dextrose like Sweet Tarts work best. Low blood sugars usually occur within three to 3 and 1/2 hours of a bolus. Obviously, if a low blood sugar occurs one or two hours after a bolus, more carbohydrate will be needed to raise the reading back to normal, than if the low happens three or four hours after the bolus. At three hours, a small amount of carbohydrate (10 to 20 grams) is usually all that's needed to remedy the situation.
Another great benefit of Humalog is that fewer lows are experienced during the night. People often needed a bedtime snack when using Regular in their pump to avoid a low during the night. In contrast, Humalog can be used at dinner with little need for a bedtime snack if the nighttime basal is correctly set.
Many research studies have reported that insulin boluses remain the same when people switch from Regular to Humalog. However, there are several reasons to be alert for changes that are likely to be needed in insulin doses. Because meals are covered more precisely with Humalog, often less insulin is needed to cover them. On the other hand, Humalog's shorter bolus action time may require a higher basal rate during the day. With Humalog, we recommend that the basal rate make up 50% to 60% of the total daily insulin dose.
In research on Humalog's biologic activity, two of six studies found that Humalog was as much as 10% more active than Regular in lowering blood sugars, while the other four found its activity was identical to Regular. So be alert if a unit of Humalog seems to go farther than a unit of Regular. Any change in insulin doses should only be attempted after discussing them thoroughly with your physician.
Many pumpers using Humalog report they need slightly less insulin through the day. Some find boluses may need to be reduced as much as 10 to 25%. Basal rate amounts generally don't change, although some find they need to raise the basal rate in the late evening and early nighttime hours because they used to rely on Regular's long action to work into the nighttime hours.
With Humalog's greater speed, basal rate changes are made closer to the actual time they are needed. For instance, on Regular, if the basal rate is raised at 2 a.m. to offset a Dawn Phenomenon, raising the basal rate might be delayed until 3 a.m. on Humalog.
For safety's sake, do not use the suspend feature with Humalog for exercise or low blood sugars. If you forget to take it out of suspend, you can quickly end up with high blood sugars. Because of its short action time, blood sugars typically begin to rise 60 to 90 minutes after the insulin is suspended, unless a bolus was taken recently. Another reason to never use suspend is that insulin which is static in the infusion line encourages clogging.
Always take Humalog by injection at the FIRST high blood sugar reading over 300 mg/dl (17 mmol). If any delivery problem occurs with Humalog in your pump, blood sugars can start to rise within 60 to 90 minutes, and ketoacidosis can begin in 4 to 5 hours. If a SECOND reading taken 90 to 120 minutes later is still over 300 mg/dl, take Humalog by injection and change out the reservoir and infusion set.
Results from 23 clinical research studies using Humalog in Europe, Canada and the United States were reported at the 1997 American Diabetes Association meeting in Boston. Our analysis of these studies found positive results in four areas when comparing Humalog with Regular:
Other results in individual studies were also positive. In one study, two people who had hypoglycemia unawareness regained warning symptoms of a low blood sugar. In a study of adolescents, incidents of nighttime hypoglycemia decreased.
The subjects in most of the research studies above were type 1's on long-term intensive management who had good control with HbA1cs in the 7s or 8s before using Humalog in the study. But one study followed people with "brittle diabetes" with erratic blood sugars and high HbA1c's. On switching to Humalog from Regular, their diabetes improved in all four areas listed above. Another study using people with type 2 diabetes also reported these improvements and the subjects had no weight gain.
Some people have noticed unexpected high blood sugars with Humalog and report that Humalog may deteriorate faster in hot weather than Regular. Control problems can certainly occur for other reasons such as incorrect basals and boluses that do not match the body's need for insulin. But Humalog appears to be less stable than Regular and more likely to lose activity, especially when exposed to heat. Test often and if your insulin does not appear to be having its expected effect, check for particles in the bottle and open a new bottle.
When Humalog goes bad, it does so quickly. Blood sugars may be fine one day and high the next. If blood sugars are unexpectedly high for any reason, check for particles, usually one or two large floaters, or several small crystals in solution or on the sides of the bottle. Always start a new bottle if you have any doubts.
In summary, the overwhelming majority of pumpers who have tried Humalog have gladly stayed on it. Most have been impressed by improvements in their control and in the convenience of taking their insulin when they eat. Fewer lows at night and improved HbA1c reports are a few of the benefits pumpers have experienced with Humalog, and many report that they feel better on this fast insulin.
For more information on Humalog and many other areas of intensive management, carbohydrate counting, glycemic index, proper insulin doses, exercise with control, pregnancy, complications, etc., get PUMPING INSULIN and the POCKET PANCREAS by John and Ruth, or STOP THE ROLLERCOASTER by John, Ruth, and Lois Jovanovic-Peterson, MD. Order these books online at (http://www.diabetesnet.com) or call The Diabetes Mall at (800) 988-4772 (011-1-619-497-0900) to order your copy.
Copyright (c) 1997, 1999 by Diabetes Services, Inc.
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