Long-acting Insulins

Adjusting The Other Insulin:
When To Bring Your Background To The Foreground

By Ruth Roberts, M.A. and John Walsh, P.A., C.D.E.
Copyright © 1997 by Diabetes Services, Inc.

Topics covered in this article:

Background Insulin Set Up Appropriately?
Changing from Regular to Humalog
Blood sugars are frequently high or low
Changing activity level
Changing weight
Menstrual period
Thyroid disease
Environmental Changes
Emotional Stress

Diabetes control is the place where two worlds collide–the world of the known and the world of the unknown. You know certain things affect your blood sugars–what you eat, how much insulin you take, when you take it, and the exercise you do. When you take charge of these areas, you often have good blood sugar readings.

But sometimes, out of nowhere, your blood sugars lose their track and start running out of control. As far as you are aware, you’re doing the same things as before. You run through your usual troubleshooting questions. But one question many people don’t get to is, “Is it time to adjust my long-acting insulin?”

Long-acting insulins, whether a dose or doses of L, UL, or NPH or the basal rate in the pump, are typically given to control the blood sugar when you are not eating. Fuel as glucose or fat is released into the bloodstream around the clock to keep the body running. So long-acting insulin or basal insulin has to be in the bloodstream around the clock to assist the movement of glucose into cells.

Long-acting insulin is background insulin–often out of sight and out of mind. Usually, that’s okay. Its job is usually less than dramatic, not responding to the turmoil, crisis, and carbohydrates of life like Regular or Humalog. It’s usually the last thing you adjust to solve a problem. But there are times when adjusting the long-acting or basal insulin has to be considered.

To control blood sugars with flexible insulin therapy, you want to know how to set up and test the short and long-acting insulins or the boluses and basals on a pump. Although you won’t end up changing your background insulin very often as you troubleshoot problems, at times this will turn out to be the most effective way to bring blood sugars back into control. When do you re-focus and make the background the foreground?

(In the following discussion, pump users please substitute “basal” for “long-acting” insulin and “bolus” for “short-acting” insulin.)

Is Your Background Insulin Set Up Appropriately?

The advantages of having the background insulin set up correctly are the control it gives your blood sugars and the flexibility it gives your life. When you use intensive management with multiple daily injections (MDI) or an insulin pump, you set up your long-acting insulin to handle your background insulin need. This means that the long-acting insulin will keep your blood sugars flat when you don’t eat. Once this has been done, you can use short-acting insulin precisely to cover carbohydrates or bring down high blood sugars, you can eat meals late with less worry about an insulin reaction or skip meals entirely when necessary, and you can sleep through the night without worrying about an insulin reaction or a high blood sugar in the morning.

A few tips to see if your background insulin is set up appropriately:

  • For most people, the background insulin makes up 50 to 60% of the total daily dose of insulin. If your long-acting insulin does not make up this percentage of your total daily dose, it has probably not been set up for MDI.
  • One of the great advantages of MDI or a pump is that each insulin has a job to do. The best test of your background insulin doses is whether they keep the blood sugar flat when you’re not eating and not taking short-acting insulin to cover your food. To see if yours is working, fast for short periods of time, and test your blood sugar often. Do this on different days until you’ve fasted and tested around the clock. (Long-acting insulins can be used to cover lunch or other meals, such as when an injection is given in the morning to cover food eaten at lunch. If this is true for you, don’t test it by fasting!)
  • Set and test the long-acting insulin dose before testing the short-acting insulin used to cover carbohydrates in a meal or snack, and to lower a high blood sugar. (The short-acting insulin is, of course, changed to match the food eaten in a meal or to lower a high blood sugar. For most exercise, the amount of carbohydrate eaten or short-acting insulin used would be altered for exercise.)
  • Don’t change your background insulin very often! Do so carefully and for solid reasons such as the ones that follow. As you make changes, review the action times of each insulin and think through the whole 24-hour period for the effect any change will have on your coverage. When you change, always consider how the change in your long-acting insulin might require you to change your short-acting insulin?

When To Consider Adjusting Your Background Insulin

When Regular is injected or bolused, it takes 30 minutes to begin working, peaks between 2 and 4 hours and hangs on for 6 to 8 hours. However, most meals raise the blood sugar for only 2 to 3 hours after they are eaten. So when Regular is taken 30 minutes before a meal, it works for several hours after the meal, meaning it actually works as a long-acting insulin.

Humalog, on the other hand, begins working in 10 minutes, peaks at 1 to 2 hours, and is gone in about 3 and 1/2 hours. Because it more closely matches the action time of most meals, Humalog is lowering the blood sugar at the same time the food is raising it.

Because Humalog has a shorter action time, this may allow blood sugars to rise between meals as the insulin level drops before the next Humalog dose is taken. To compensate for this, doses of long-acting insulin may need to be increased when Humalog is started and less Humalog may be needed for meals than Regular.

One current trend is to use smaller, more frequent doses of long-acting insulin to provide a more stable level of background insulin throughout the day. If you are having difficulty maintaining control on Humalog, consider adjusting the long-acting insulin.

Frequent highs or lows can be caused by many things, but this is one of the most common signs that your long-acting insulin is not set up to cover your background need.

Review the previous section for ways to test whether your background insulin is set up appropriately. Also, look at Table 1 for the action time of the long-acting insulin you use. Your long-acting dose may be too high if you have frequent low blood sugars or a pattern of lows when the long-acting insulin is peaking, or your blood sugar drops when you skip a meal. Your long-acting may be too low if you have frequent highs or your blood sugar rises when you skip a meal.

Physical activity and physical fitness determine much of our sensitivity to insulin. A marathon runner, for example, may need only half as much insulin circulating in the blood as a person who doesn’t exercise regularly. The need is lower because of increased sensitivity to insulin. Whenever there’s a substantial increase in the level of activity or fitness, a reduction in the long-acting insulin is almost always required. (Regular or Humalog also needs to be reduced, especially if the activity is short or intense and for events, a person has not trained for.) For example, if you work as a moderately active flight attendant but are going to spend two weeks on a bicycle trip, plan on lowering your long-acting insulin doses.

Just the opposite is needed when your activity level decreases. If you have been working as a framer on a construction crew, but now work at a desk as a project cost estimator, this decrease in activity is likely to increase your need for long-acting insulin.

Your bathroom scale is a barometer of your insulin doses. When you weigh more, you need more long-acting (and short-acting) insulin. But as your weight drops, your sensitivity to insulin increases and your long-acting insulin will need to be lowered.

The speed of the weight change mirrors how quickly your insulin needs change. If you go on a restricted-calorie diet to shed pounds quickly (swimsuit season suddenly upon you), you may need to quickly reduce your long-acting insulin by 10 to 30 percent.

How much weight is lost or gained is also important. A gradual change of 5 pounds or so may have little effect on the long-acting insulin doses. If the shift is 10 pounds or more, a reduction or increase in these doses will likely be needed.

Gastroparesis is damage to the nerves that control the wavelike motion of the intestines. This disorder delays the absorption of food after a meal. When short-acting insulin is taken to cover food, an insulin reaction often occurs in 2 to 3 hours, followed by a high blood sugar some 6 or 8 hours later as the meal is converted to glucose in the blood.

To match this delayed absorption, a person with gastroparesis may benefit from a higher than normal dose of long-acting insulin in the morning to cover eating, with less short-acting to cover meals.

Keep in mind, most control problems have nothing to do with gastroparesis. So always consult with your physician about this.

Illnesses place extra stress on the body and often require extra short-acting and long-acting insulin to fight this physical stress.

Bacterial infections, like pneumonia, strep throat, an impacted wisdom tooth, a bladder infection or a sinus infection, are often accompanied by a fever and can cause the total insulin need to double. In fact, an unexplained high blood sugar that’s difficult to bring down can be the first sign of an infection. The quick action of short-acting insulin is usually needed to lower a high caused by infection. Doses of short-acting insulin can be repeated every few hours, as needed. After an antibiotic is started, however, any temporary increase in insulin dose has to be quickly lowered to prevent insulin reactions.

Illnesses that last several weeks, like hepatitis and mononucleosis, often require an increase in the long-acting or basal rate insulin doses. Shorter viral illnesses, like a cold or flu, have more varied effects on the blood sugar. Control is usually easier to achieve during short term viral illnesses by using extra short-acting insulin for the high blood sugars rather than raising the long-acting insulin. During an illness, extra short-acting insulin may be needed for meals even though eating is reduced.

Illnesses that cause vomiting or diarrhea may mean you can’t eat, but they do not affect the need for background insulin. Reduce or eliminate your short-acting insulin if you are not eating and your control is good, but continue to take your long-acting or basal rate insulin.

Be sure to test your blood sugar more often or ask someone else to test it during any illness. If your blood sugar is high and has been for a while, test for ketones, and be sure to drink lots of liquids.

Many women find their blood sugar rises in the days just before their period begins. If this increase is small, it may not require increasing long-acting insulin. But for many women a substantial increase in both short-acting and long-acting insulins during the few days prior to their period improves premenstrual symptoms and blood sugar control. The need for extra insulin quickly returns to normal on the first day of the period, so the insulin doses should be adjusted to the previous levels at that time.

Certain drugs increase the need for insulin and cause a rise in the blood sugar if extra insulin is not taken. Primary among these are steroids or glucocorticoids like prednisone and cortisone. Whether taken for poison ivy, lupus, asthma, or injected into an inflamed joint, steroids generally raise insulin need sharply, sometimes to 3 or 4 times previous levels. The need will last as long as the drug is taken. If steroids are injected into a joint, extra insulin may be needed for 3 to 5 days.

Whenever these medications are prescribed they can affect blood sugar levels. Contact your diabetes care provider immediately to discuss how to increase your insulin. Often both short-acting and long-acting insulins need to be increased.

Thyroid disease occurs fairly often with both types of diabetes. It occurs with Type 2 because it is more common as we age. In fact, one out of every 10 women over age 65 has thyroid disease. It is also more common in Type 1 because Type 1 and thyroid disease can both result from an autoimmune attack on hormone-producing glands.

Thyroid disease occurs gradually over a period of weeks or months. It may begin as a production of too much thyroid hormone and then gradually change to too little thyroid production. Because thyroid disease occurs gradually and may cause high (overactive thyroid) or low (underactive thyroid) blood sugars, the reason for the loss of control is often difficult to identify. If your blood sugars have changed and you have thyroid symptoms like nervousness, feeling hot or cold, tiredness or difficulty sleeping, have your thyroid checked. If you have a low thyroid level and are placed on thyroid medication, you will probably need to raise your insulin doses slightly to control your blood sugars, especially if you have adjusted your insulin doses downward as your thyroid became less active.

When some aspects of your external environment change, your body adjusts by changing its use of glucose and fat. In hot weather, the body uses more energy in cooling itself. It increases circulation to send more blood flow to the skin, which picks up insulin faster from an injection or infusion site and speeds up the action of insulin. Most people are more active in the summertime and have less fat in their diet, as well. As these things happen, less background insulin may be needed to keep the blood sugar controlled during the summer, while just the opposite happens over the winter months.

Metabolism increases in two other circumstances, creating a need for you to lower your background insulin. If you are outside during very cold weather and find yourself shivering, your control may be better with less insulin. Similarly, at higher altitudes, more energy is needed to breathe and pump blood as the air becomes thinner, especially in the first few days after you arrive at a higher elevation. Until the body acclimates, less long-acting insulin or more carbohydrate may be required.

Emotional stress may raise the blood sugar, calling for an increase in insulin. Many times stress isn’t obvious until it’s already caused a rise in the blood sugar. When this happens, use an injection of short-acting insulin to bring down the high blood sugar.

If you anticipate a short period of stress, such as a day of tension-filled business meetings, check your blood sugar often and take more short-acting insulin if it goes high. If you are going through a long stressful period, such as a family member in the hospital, consider raising your background insulin to help your control and coping skills.

  • When changing from Regular to Humalog (injections or pump)
  • When blood sugars are frequently high or low
  • When changing activity level
  • When changing weight
  • Gastroparesis
  • Illnesses
  • Menstrual period
  • Medications
  • Thyroid disease
  • Environmental Changes
  • Emotional Stress

If none of this seems to be working, start from scratch and again set and test your background insulin. Then set and test your carb coverage and high blood glucose coverage. Reset and retest until you’ve improved your control. Consider also using different background insulin than the one you’ve been using if yours does not peak at the time you need it to. This will likely call for timing the doses differently, too. If you’re on a pump, consider different basal rates for different times of the 24-hour period. Make only one change at a time and see the effects for several days before moving on. Be patient and keep looking until you find an approach that helps your control.

For more information on insulin adjustment and many other areas of intensive management, carbohydrate counting, glycemic index, proper insulin doses, exercise with control, pregnancy, complications, etc., get Pumping Insulin by John and Ruth, or Using Insulin by John, Ruth, and Chandrasekhar Varma, MD FACE FACP and Timothy Bailey MD FACE FACP. Order these books online or call The Diabetes Mall at (800) 988-4772 (011-1-619-497-0900) to order your copy.