Some people recently diagnosed with T1DM can use a pump immediately, but most people who decide to start using a pump are switching from the following routine:
i Long-acting insulin once or twice a day, which corresponds with the basal insulin of the pump i Multiple daily injections with rapid-acting insulin before meals, which corresponds to the boluses given by the pump
The total insulin dose from a pump is about 20 percent less than the amount of rapid-acting plus long-acting insulin from needles or other types of injection methods. This reduction is due to the fact that a constant infusion of insulin is more effective than multiple shots.
A pump can be started with a few or many durations of different basal rates, but in the beginning, the basal rate for most patients is broken down into these time frames: midnight to 3 a.m., 3 a.m. to 7 a.m., 7 a.m. to noon, noon to 6 p.m., and 6 p.m. to midnight. The rate of flow of the insulin, whether 1 unit per hour, 0.5 unit per hour, or whatever a particular patient needs, is determined by the measurement of the response with finger-stick blood glucose tests. For example, the patient may be started on 0.5 unit per hour throughout each time frame. If the morning blood glucose is above the desired fasting level listed in Chapter 10, the infusion of insulin in the time frame prior to that time may be increased to 0.6 unit per hour.
If you're the type 1 diabetes patient and your schedule is different than that of most people, you can adapt the schedule to your life. For example, if you work the night shift, you may reverse the preceding schedule.
Suppose that your child takes 5 units of rapid-acting Lispro insulin before meals and 5 units of long-acting glargine insulin at bedtime. The total is 10 units. With an insulin pump, he should start with 20 percent less, so his total dose starts at 8 units.
1 He may take 0.2 unit per hour from midnight to 3 a.m. for a total of 0.6 unit.
1 He needs more insulin just before awakening to deal with the dawn phenomenon, the tendency to have higher blood glucose tests first thing in the morning (see Chapter 4), so he takes 0.3 unit from 3 a.m. to 7 a.m. for a total of 1.2 units.
1 At 7 a.m., he takes a bolus to cover his breakfast carbohydrates, assuming he's eating within ten minutes. Suppose that he takes 1 unit before breakfast.
1 From 7 a.m. to noon, he takes a little less, say 0.2 units per hour for a total of 1 unit.
1 At noon, he again takes a bolus to cover his lunch — 1 unit again.
i Your child continues the basal insulin at the same time. He may drop his basal rate to 0.15 unit between noon and 6 p.m. for a total of 0.75 unit and keep it to 0.15 unit again from 6 p.m. to midnight for 0.75 unit. The total units from noon to midnight is 1.5.
1 He shouldn't forget to take that pre-supper bolus, perhaps 2 units.
Adding up your child's basal and bolus insulin, he's taking 8.3 units initially. Then it becomes important to check his blood glucose before meals and occasionally one hour after eating and in the middle of the night (see Chapter 7
for details on monitoring blood glucose). With the readings and knowing the amount of carbohydrates he's about to eat, you and your child can adjust the size of his boluses to achieve the levels in Chapter 10.
How often should you and your child make changes in the basal rate? If all is well, you can fine-tune it once or twice a month. If his body is changing rapidly due to sickness, increased daily physical activity, and so forth (or due to pregnancy if you're the patient), changes may need to be made much more often than that, perhaps even daily.
One way to easily determine if your child's basal rate is correct is to check his blood glucose before he would normally eat a meal, don't take a bolus and don't eat the meal, and then check his glucose an hour later. If his glucose remains about the same, his basal rate is good. Do the same thing with each meal over a day, if possible, to get the complete picture.
Changes made in the basal rate affect your child's blood glucose two hours later. For example, a change made at 2 p.m. is felt at 4 p.m. To counteract the delay, a bolus dose equal to two hours' worth of the basal rate will result in a more immediate response of blood glucose. In contrast, stopping the pump for two hours rapidly reduces the effect of the basal rate on blood glucose. If you want to rapidly affect the blood glucose, do it by giving a bolus dose, not by changing the basal rate.
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