This chapter and the next describe a number of specific insulin regimens. As you read, please refer back to Table 17-1 (here) for descriptions of the various insulins and their speed of action—for instance, our long-acting insulin will be Levemir.
The particular regimen that suits you will depend to a considerable degree upon your blood sugar profiles. Your physician must decide whether you need long-acting insulin to cover the fasting state, short-acting insulin to cover meals, or both. In either event, she will require blood sugar profiles and related data, covering as many days as she designates, prior to every office visit or telephone call for fine-tuning of doses. Remember that “related data” includes the times of meals, whether you overate or underate, the times of exercise (including seemingly inconsequential activity such as shopping), the times and doses of blood sugar medications, infections or illnesses you may have had, when and how many glucose tablets you took to correct a low blood sugar—in short, anything that might have affected your blood sugar. Bedtime blood sugar readings are especially important information, because an increase or decrease overnight should most certainly affect the determination of your bedtime dosage of longer-acting insulin.
To give you some examples of how we might use insulin to bring your blood sugar levels into target range, let’s consider the following blood sugar profile scenarios.
Let’s say you’re taking the highest useful dosage of an insulin-sensitizing agent (ISA) at bedtime. Your fasting (i.e., before-breakfast, empty-stomach) blood sugars are still consistently higher than your bedtime blood sugars. Because of this, you probably require long-acting insulin at bedtime. Before we’d start you on insulin, however, we’d examine your data sheet carefully in order to make certain that you finished your last meal of each day at least 5 hours prior to your bedtime blood sugar measurement. No one should be given a long-acting insulin to cover an overnight blood sugar increase caused by a meal unless delayed stomach-emptying (see Chapter 22) is present.
For people who customarily sleep 8 hours or longer, we usually start with long-acting Levemir at bedtime. Because of the dawn phenomenon (see here), a result of rapid removal of insulin from the bloodstream by the liver near the time of arising in the morning, it’s wise to take this dose no more than 8½ hours before the morning dose. The bedtime insulin will usually appear to have lost much of its action 9 hours after the injection but will start working again after about 3 hours—when the dawn phenomenon ceases.
For type 1 diabetics and for some type 2s, Levemir does not usually last the entire night, despite claims to that effect by the manufacturer. This is also true of Lantus, the “long-acting” insulin that I don’t recommend. If a bedtime injection of Levemir lasts the entire night, it may be because the dose you injected is so large that blood sugar drops too low in the middle of the night. It is therefore wise to set an alarm for 4 hours after the bedtime dose to make sure your blood sugar is not more than 10 mg/dl below your target. If it is, you will have to split your bedtime dose into two doses, each slightly less than half the initial dose, one taken at bedtime and the other 4 hours later. This inconvenience was not necessary with the old ultralente insulin that was discontinued by Eli Lilly and Company because it was considered to be unprofitable. This is just another reason why I believe diabetes is generally treated as an orphan disease, where profit is more important than the patient.
Your physician may want to use this simple method for estimating your starting bedtime insulin dose. Generally, 1 unit of regular, NPH, or long-acting insulin* lowers blood sugar 40 mg/dl for a 140-pound, nonpregnant adult whose pancreas produces no insulin. Since your beta cells may still be producing some insulin, we’d abide by the Laws of Small Numbers and cautiously assume initially that 1 unit of regular, NPH, or Levemir would, over a period of hours, lower your blood sugar 80 mg/dl, just so we wouldn’t bring it dangerously low and risk hypoglycemia.
We would then proceed as follows.
First, we’d look at your blood sugar profiles. The first number we want is the minimum overnight blood sugar increase over the past week. For each night, we’d subtract your bedtime blood sugar from your fasting blood sugar for the following day, then use the difference for the night with the lowest rise. For this calculation, bedtime must be at least 5 hours after finishing supper. For small children, we accomplish this by asking parents to get a painless “tushy stick” while the child is sleeping.
The second number we’d want is the maximum amount that we’d expect 1 unit of long- or intermediate-acting insulin to lower your overnight blood sugar. To get this number, we’d take the maximum anticipated blood sugar drop from 1 unit. Since our initial conservative rule of thumb is that 1 unit of Levemir or NPH will lower a 140-pound type 2’s blood sugar by 80 mg/dl, we would divide 140 by your weight in pounds and then multiply the result by 80 mg/dl. If your weight is 200 pounds, the equation would look like this: (140 ÷ 200) × 80 = 56. So your initial estimated blood sugar drop will be 56 mg/dl from 1 unit.
Let us assume, for example, that your lowest overnight blood sugar rise in the past week was 73 mg/dl. We’d take 73 mg/dl and divide it by the number you derived from the above equation, or 56. Your trial bedtime dose of Levemir would be 73 ÷ 56 = 1.3 units. This is your starting bedtime dose. Rounding off the dose to the nearest ¼ unit gives you 1¼ units, which you can abbreviate on your data sheet as 1+ L, or just over 1 unit.
That was pretty easy, but it was only a starting point. Most probably this dose won’t be perfect—likely too low or possibly even a little too high. To fine-tune the bedtime insulin, you merely record bedtime and fasting blood sugars for the first few days after starting the insulin. If the minimum overnight blood sugar rise was less than 10 mg/dl, you’ve likely hit the proper dose on the first try. If the rise was greater, your physician may want you to increase the bedtime dose by as little as ¼ unit every third night, until the minimum overnight rise is less than 10 mg/dl.*
Even one overnight hypoglycemic episode can be quite frightening, especially if you live alone. Such an event can easily turn you off to insulin therapy, so it’s wise to take some simple precautions to ensure it doesn’t happen. On the night that you take your first shot (and on the first night of any increase in dosage), set your alarm clock to ring 6 hours after your bedtime injection. When the alarm sounds, measure your blood sugar, and correct it to your target value if it’s too low (see Chapter 20, “How to Prevent and Correct Low Blood Sugars”). Even one low blood sugar event suggests that the bedtime dose should be reduced.
With the possible exception of growing teenagers, people with infections or delayed stomach-emptying, and the obese, most of us usually require less than 8 units of Levemir at bedtime.
Levemir in doses greater than 7 units, in addition to creating a lower blood sugar, tends to last longer. This may be responsible for blood sugars that are too low in the late morning, or even in the afternoon. There are at least two ways to prevent this. First, you can split the insulin into two or more approximately equal doses. These should be injected at bedtime, but into different sites. If your required dose is 9 units, you might inject 4 units into your arm and the other 5 into your abdomen. You may recall that large doses are not absorbed with consistent timing or total action, so two or more smaller injections have the advantage of making the absorption of both doses more predictable. The same syringe can be used for the second, third, and so on.
The most effective way to generate level blood sugars throughout the night was suggested by Pat Gian, the woman who runs my office: split the bedtime Levemir into two approximately equal shots, one taken at bedtime and the other taken 4 hours later.
If your blood sugar rises during the day even though you’re taking the maximum dose of one or more ISAs to cover meals, it’s time for you and your physician to perform another experiment.
This time you want to determine whether meals have caused your increase or whether blood sugar has increased independently. It’s very unusual, by the way, for fasting blood sugars to rise during the day if you don’t require insulin at bedtime, usually to compensate for the dawn phenomenon (which, as we’ve said, is the tendency in many diabetics for blood sugars to go up overnight, and perhaps for up to 3 hours after arising). In order to determine when and how much your blood sugar is rising during the day:
Start your day with a blood sugar measurement.
If you’re taking an ISA in the morning, continue with your present dose.
Check blood sugar again 1 hour after arising.
Do not eat breakfast or lunch, but plan on supper—at least 12 hours after this second morning blood sugar measurement.
During the day, continue to check blood sugars approximately every 4 hours, and certainly 12 hours after the second morning test.
If, even with a maximum dose of your ISA, your blood sugar rises more than 10 mg/dl during the 12-hour period—without any drops along the way—you probably should be taking a long-acting (that is, basal) insulin when you arise in the morning.*
This dose of basal insulin is calculated the same way we calculated the bedtime dose in the first scenario. Because fasting twice in one week is unpleasant, we may try to wait another week before performing this experiment again to see if our basal dose is adequate. Further experiments in subsequent weeks may be necessary for fine-tuning of this insulin dose.
Once you take insulin, it is essential that you and your family be familiar with the prevention of hypoglycemia (low blood sugar). To this end, you and those who live or work with you should read Chapter 20, “How to Prevent and Correct Low Blood Sugars.”
If you are taking only longer-acting insulin as described in this chapter and are strictly following our dietary guidelines, it might not be necessary to measure blood sugar every day for life. Nevertheless, it’s wise to assign one day every week or two for measuring blood sugar on arising, right before and 2 hours after meals, and at bedtime, just to make sure that your insulin requirements are not increasing or decreasing. If any of your blood sugars are consistently 10 mg/dl above or below your target, advise your physician.*
It’s essential that you also measure blood sugar before and after exercising. If, in your experience, your blood sugar continues to drop one or more hours after finishing your exercise, you should check your blood sugar hourly until it levels off.†
As you shall read in Chapter 21, “How to Cope with Dehydration, Dehydrating Illness, and Infection,” it is important whenever you suffer such an illness to secure daily blood sugar profiles and report them to your physician.
Many patients and physicians routinely increase the basal morning dose if before-breakfast blood sugars are repeatedly elevated. This is the wrong dose to change. It’s the bedtime dose that controls fasting blood sugar, and therefore that dose should be adjusted accordingly. After fine-tuning of bedtime and, if necessary, morning doses of long-acting insulin, your pancreatic beta cells may recover enough function eventually to prevent a blood sugar rise after meals. This frequently turns out to be the case for mild type 2 diabetics. If, however, you still routinely experience a blood sugar rise of more than 10 mg/dl at any time after any meal, you’ll probably require premeal injections of a rapid-acting insulin, as described in the next chapter.
Some people experience a sudden decline in their insulin requirements when a long period of cool weather (e.g., winter) is abruptly interrupted by significantly warmer weather. This phenomenon can be recognized by blood sugar well below target when the weather suddenly becomes warmer. In such individuals, insulin requirements will rise in the winter and drop in the summer.* The reason for this effect is speculative, but may relate to the increased dilation of peripheral blood vessels during warm weather and the resultant increased delivery of blood, glucose, and insulin to peripheral tissues. Whatever the cause, keep careful track of your blood sugar whenever the weather warms suddenly, since potentially severe hypoglycemia can result if insulin dosages are not adjusted.
Long-distance travel that requires you to shift your clock by 2 hours or less shouldn’t have a major effect upon your dosing of ISAs or basal insulins covering the fasting state. It should certainly have no effect upon the use of rapid-acting insulin or insulin-sensitizing agents intended to cover meals. A problem does arise when travel shifts the time frame by 3 or more hours and you’re taking different doses of long-acting medication in the morning and at bedtime. The situation becomes particularly complex if you travel halfway around the world, so that day and night are reversed.
When the time shift amounts to 2 hours or less, you need only take your morning medication upon arising in the morning and your bedtime medication at bedtime. One solution to handling larger time shifts is to effect a gradual transition, using 3-hour intervals over a period of days. To do this, you must keep track of the time “back home.” If, for example, you’re traveling east, so that the time back home is earlier, on your first day away you would take both of your basal doses 3 hours later on the “back home” clock. On the second day, you would take them 6 hours later, and so on. Thus, if your new location to the east of home is in a time zone 6 hours later than it was at home, it would take you 2 days to achieve a full transition. You would do just the opposite when traveling west. This procedure can be inconvenient because it requires that you set an alarm clock for absurd hours just to take an insulin shot or a pill—and then, you hope, go back to sleep.
Several of my patients routinely save themselves this kind of annoyance when they travel. At their destinations, they continue to take their morning dose when they arise in the morning and their bedtime dose when they go to bed. They check their blood sugars every 2 hours while awake and lower them, if too high, using the method described in Chapter 19, “Intensive Insulin Regimens.” If their blood sugars drop too low, they raise them using the method described in Chapter 20. Frankly, this is the approach I use myself. Neither I nor my patients have gotten into trouble this way. This carefree approach can cause problems if the bedtime dose is considerably different from the morning dose. If this is the case, the gradual transition of 3 hours per day is certainly safer.
My patients and I have observed that as larger doses of insulin are injected, the effects upon blood sugar become less predictable. This is due in part to day-to-day variations in absorption of large injections. After some trial and error, I arrived at a cutoff point of 7 units as the largest single injection I would want an adult to take (smaller for children). Therefore, if an insulin-resistant patient requires 20 units of Levemir at bedtime, I ask him to take 3 separate injections in 3 separate sites of 7 units, 7 units, and 6 units, all using the same syringe.
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