Читать книгу Transitions in Care - Howard A. Wolpert - Страница 17

The insulin profile shown in Figure 2 may be familiar to you. In this traditional approach to insulin replacement, there are two injections of rapid-acting insulin (Apidra, Humalog, Novolog, or regular) at breakfast and dinner and two injections of a longer-acting insulin (NPH) to provide your body with basal insulin. Typically, the rapid-acting and longer-acting insulins are either premixed in one vial or one pen, or you can mix the two insulins into one syringe, so that you administer two injections per day, with two different insulins in each injection. The rapid-acting insulin injections take care of the carbohydrates eaten at breakfast and dinner, while the morning injection of NPH covers lunch and the evening injection of NPH controls the sugar that the liver releases into the bloodstream overnight. Striving for good glucose control using this type of insulin program can be challenging. These are some of the constraints:

If lunch is delayed, the morning injection of NPH will kick in and hypoglycemia (low blood glucose reaction) could result.

Snacks will often need to be eaten between meals (especially mid-morning and bedtime) to prevent the long-acting insulin from causing hypoglycemia.

Lunch and snacks will need to have a consistent carbohydrate content. If you eat too many carbohydrates, there may be insufficient insulin in the system and the blood glucose level will end up rising. If you eat too few carbohydrates, there may be more insulin in your body than you need to cover your food, and your blood glucose level may fall.

Waking times in the morning need to be consistent from one day to the next. If you get up later in the morning, the longer-acting insulin taken the evening before (to control the production of glucose by the liver overnight) may be running out, and the end result will be an increased glucose level.

Hypoglycemia in the middle of the night can occur if a bedtime snack is not consumed.

FIGURE 2 Injection therapy using Humalog/Novolog and NPH/lente. In this approach, there are two injections of rapid-acting insulin at breakfast and dinner and two injections of NPH/lente insulin to provide the basal insulin. B, breakfast; L, lunch; SN, snack; SUP, supper.

As with most choices in our lives, there is a tradeoff with these insulin programs. There is no need for a lunchtime injection, which can be an important consideration for someone who would find this extra injection inconvenient or impractical at school. But if you want to keep your glucose levels within any targeted range, you need to follow a fairly regimented and consistent routine and meal plan. This means that meals and snacks need to be eaten at specific times, and the carbohydrate content of meals needs to be consistent from one day to the next. To address the risk of hypoglycemia in the middle of the night, some people will administer the rapid-acting insulin at dinner and the longer-acting insulin at bedtime. That way, the NPH is not peaking at 2:00 a.m. when you are asleep. This choice of an insulin regimen means administering three injections per day.

The development of peakless long-acting insulins and insulin pumps has presented new options for insulin replacement. With these tools, we can be closer to mimicking the way the beta-cells of the pancreas release insulin into the body.

This approach to insulin replacement (shown in Figure 3)—also known as basal/bolus therapy—allows more flexibility in a person’s schedule and eating. Insulin can be matched to cover the amount of food eaten, and there’s no need to eat on schedule. In addition, because the longer-acting insulin does not peak, there is no need to eat snacks between meals to prevent hypoglycemia. This can be quite helpful with weight control (see page 32). But this type of insulin program generally requires more injections per day or the use of an insulin pump.