Ideally, if your basal insulin (insulin glargine, detemir, NPH, or pump basal) dose is correct, then even if you did not eat and had your normal activity, your glucose levels will stay in the normal range. This is usually not true in practice, and there is always some drift in your glucose levels. This is because of the day-to-day variability in the absorption of the injected insulin and the way the body responds to the insulin. Your goal is to minimize the upward and downward drift of your glucose levels.
So, how do you determine if your basal insulin dose is correct? You do this by looking at your glucose levels after eliminating the variables of food, exercise, and bolus insulin. Usually, overnight is the easiest time to assess your basal insulin needs:
• Eat early in the evening, and limit your carbohydrates so that by bedtime there is no effect of the evening bolus and your stomach is empty.
• Provided your glucose at bedtime is in the safe range—say 100 to 150 mg/dl, then you can set your alarm and check blood glucose levels at 2 a.m. and then again at 6 a.m. and 9 a.m. If your glucose levels drift up or down, you need more or less basal insulin respectively.
Once you have determined that your overnight basal is satisfactory, then you can work on determining the basal doses during the day. The principal is the same—you want to look for glucose drift after you eliminate the effect of food, bolus insulin, and exercise. Instead of fasting all day, try limited fasts:
• If you want to know that your morning basal dose is correct, then on a day when your fasting glucose is on target, do not eat breakfast or give bolus insulin, and instead plan to eat an early lunch. You can check glucose levels throughout the morning and look for glucose drift.
• If you are interested in determining whether the early afternoon basal doses are correct, eat breakfast but delay or skip lunch.
• If you are interested in late afternoon basal doses, then either have an early lunch with limited carbohydrates or skip lunch.
• If you are interested in early evening basal doses, delay dinner. An early dinner or skipping dinner will allow you to evaluate late evening basal doses.
You need to confirm your observations because of day-to-day variability. In other words, after checking glucose levels overnight, if you think that your glucose levels are drifting upward and that you need more basal insulin, check again (preferably twice) to make sure this is a consistent finding before making the intervention. If you perform the above analysis you may find
• Your glucose levels are stable if you do eat or give bolus insulin—your once-daily dose of injectable basal insulin or pump basals are working just fine.
• Your glucose value drifts downward or upward overnight and you need to increase or decrease your basal insulin respectively.
• Your glucose levels are stable most of the night but shoot up at around 5 to 6 a.m. In other words you have a strong dawn phenomenon. If you are on an insulin pump, you can adjust the basal rate on your pump to cover this dawn phenomenon. If you are on a long-acting basal insulin injection you have several options:
• Carefully increase your nighttime insulin to see if you can get away with it—the concern is that you might go low earlier in the night.
• Change your basal insulin. For example, if you are on insulin glargine, you could try insulin detemir, which has more of a peak.
• Wake up at 5 a.m. every day and give a little bolus insulin.
• This is a good reason for switching from insulin injections to an insulin pump (see Chapter 6).
• Your glucose levels drift up midafternoon when you do not eat lunch or give a bolus. This tells you that your injected basal insulin is not lasting twenty-four hours or you need to increase the afternoon basal rate on your pump. If this occurs on long-acting basal injection, then I would recommend splitting your basal insulin and giving it twice a day. Usually you will need more in the evening to cover the dawn phenomenon and a smaller dose in the morning.
Once you have determined that your basal doses are reasonable and that any drift is minimized, you cannot assume that they will stay the same. They will change for a number of reasons:
• Change in activity is an obvious cause—often, people find that they have to increase their basal insulin during winter, when they are spending more time indoors.
• Stress can have an impact—some people find that they need more insulin when they are stressed.
• There can be changes relating to the menstrual cycle. Some, but not all, women find that they need more insulin in the second half of their cycle, especially the five days before their period. As soon as their period starts, they become more sensitive and have to cut back on their basal insulin. If you are on a pump, it is quite easy to use a different set of basals for different times of your cycle.
I do want to emphasize that assessing basal doses is a reiterative process—you should evaluate them on a regular basis.
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WHAT IT IS A three-phase plan that has been likened to the low-carbohydrate Atkins program because during the first two weeks, South Beach eliminates most carbs, including bread, pasta, potatoes, fruit and most dairy products. In PHASE 2, healthy carbs, including most fruits, whole grains and dairy products are gradually reintroduced, but processed carbs such as bagels, cookies, cornflakes, regular pasta and rice cakes remain on the list of foods to avoid or eat rarely.