insulin pumps

Adjusting Your Basal and Bolus Rates

Managing diabetes is hard work. It can also be very discouraging when you are making a consistent effort to manage your blood glucose, and your efforts are rewarded by unpredictable high and low blood-glucose readings.

Insulin-pump therapy can help improve blood-glucose control. Unfortunately, the pump is only a tool and, like any tool, it requires a skilled operator. Wide blood-glucose swings and elevated HbA1c levels are still possible, even when using a pump.

Achieving the best results on pump therapy requires attention to detail and frequent blood-glucose monitoring.

Tips for Fine-tuning Your Pump Regimen

Often, individuals are placed on an insulin pump without a good understanding of how to adjust their doses to achieve the best results. So, if you are interested in fine-tuning your insulin-pump regimen, here are some tips to get you started:

Basal Rates

You have the ability to program 24 or more different basal rates in your pump. But how do you know how much you need and when?

If your basal rate is set correctly, your blood sugar should remain stable (within 30 points) as long as you are not eating. In order to find out if your basal rate is set correctly, you will need to fast for a period of time.

Bolus Rates

An accurate insulin-to-carbohydrate ratio is essential to meet your blood-glucose goals. However, for many people, the insulin-to-carbohydrate ratio may be different at different times of the day. It's not unusual to require more insulin at breakfast for the same amount of carbohydrates that you eat at lunch.

Fix the Fasting First

A general rule for insulin dose adjustments is to fix the fasting first. This means before you start worrying about blood sugars for the rest of the day, make sure you are waking up in your target range.

As anyone with diabetes can attest, starting the day with a blood sugar that is too high or low can dramatically affect the rest of the day. For this reason, it is recommended that you test the overnight basal rate first. In one sense, the overnight basal rate test is the easiest test to perform because most people do not typically eat during the night. On the other hand, it does require that you get up during the night to measure your blood glucose.

Fixing Your Overnight Basal Rate

In order to determine if your overnight basal rate is set correctly, you will need to take your evening bolus no later than 6 p.m. The first step is to check your blood sugar four to five hours after your last bolus (four hours for Humalog,Novorapid or Apidra- short acting insulin analogs- users and five hours for Regular insulin users). If your blood sugar level is in your target range, you can begin the test. If it's too high, you will need to take a correction bolus and bring it down. If it's too low, you will need to eat something. Either way, you will not be able to perform the overnight basal rate test until your sugar level is normal.

Once your blood glucose is in your target range, begin the test by dividing the overnight hours into testing "windows" of no more than four hours in length. For example, if you take your last short acting insulin analogs bolus at 5 p.m. and go to bed at 11 p.m., you will want to check your blood glucose at 9 p.m., at bedtime and at least once during the night. This will provide you with three testing windows.

If your basal rate is set correctly, these blood glucose readings should not vary by more than 30 points. A drop or rise in blood glucose between testing windows may indicate a need for a change in your basal rate(s). If your blood glucose during the night is low, you will need to eat a snack. If it is high, you will need to take a correction bolus. Either action will negate the rest of the test, but you will have an indication that part of your evening basal rate is incorrect.

As everyone with diabetes knows, what happens one time is not always indicative of what will happen next time. So, it is best not to change your rates based on one basal rate test. Try repeating the test to see if you get the same results. If you do, consider changing your basal rates in 0.1 unit increments. Remember it is always best to adjust you basal rates with a little help of your diabetes-care team.

Ramiro Antuña de Alaiz
Diabetes Treatment Unit

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