Tweaking an Extended Bolus
If you’ve ever tried to use your insulin pump’s extended bolus feature (combo bolus, square/dual wave bolus) and it was a flop, we can help you figure out what went wrong. And how to fix it! Find out where to start when using an extended bolus, how to adjust the settings based on the blood sugar results that follow, and what to do if an extended bolus isn’t enough…
In the preceding article Extended (Combo, Dual/Square Wave) Bolus we talked about when to use this handy insulin pump feature.
– there’s an initial drop in blood glucose followed by later high blood glucose, and
– the meal was low GI, high protein, and/or high fat, and
– the basal rates, I:C ratios, and carb content have all been confirmed as accurate,
– an Extended Bolus may be helpful for smoothing out the post-meal valleys and peaks.
If that is the case, we suggested that you experiment with the Extended (Dual/Square-Wave/Combo/Multi-wave Bolus) feature of your child’s insulin pump: try an initial combo bolus, monitor blood glucose closely (wise whenever you mix up the management routine!) by checking and recording the blood glucose results at 1-hour post-meal and a few times (1-2 hours apart) in the hours following the meal. This will give you the data needed to determine the effect of the Extended Bolus.
But where should you start? And what should you do with the results?
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Where to Start with an Extended Bolus
An appropriate split of the Normal and Extended portions of the Extended Bolus depends upon a number of factors, including:
- the GI of each of the foods eaten
- the combination of foods eaten (Is your child eating a large proportion of low-GI foods? Mostly moderate-GI foods? Mostly a high-GI food with some small amount of low-GI food on the side? Each of these situations would benefit from a different insulin split.)
- the fat and protein content of the meal
- individual differences
We suggest that you wade into the (dual) wave with a conservative starting point, and carefully analyze the results:
How to Adjust the Split Based on the Results
If your child just ate pasta using an Extended (Combo) Bolus for the first time, and the resulting blood glucose flat-lined at 6.0 mmol/L for the following 12 hours, then congratulations! Your experiment is done.
But for the other 99.9% of us, a bit of post-experimental data analysis would be helpful. Here are some things to consider:
If blood glucose drops early in the meal despite the use of an Extended Bolus, this may indicate that too much insulin is still being delivered up front: try a smaller number for the 1st part of the ratio. For example, if your initial split was 50/50, you could try 40/60, or even 30/70.
Conversely, if blood glucose rises significantly early after the meal, this could mean that not enough insulin is being delivered up front: try a larger number for the 1st part of the ratio. For example, if your initial split was 50/50, you could try 60/40, or even 70/30.
If blood glucose is steady for the first few hours around the meal time, but rises suddenly a few hours after the meal, this may indicate that the insulin “tail” is too short: try spreading the extended portion of the bolus over a longer time period. For example, if initially you used a 50/50 combo over 3 hours, you could try extending the same split over 4 hours.
Extended Bolus Not Enough to Manage Post-Meal Spikes?
For meals with a high fat content, you may find that, in addition to using a Combo Bolus to address slower digestion, it may be helpful to set a temporary basal rate increase to address the insulin resistance that comes from fat intake. In these cases, check out the Double Whammy Approach in WaltzingTheDragon.ca’s Adjusting for GI Level article.
The above information was reviewed for content accuracy by clinical staff of the Alberta Children’s Hospital Diabetes Clinic.
This material has been developed from sources that we believe are accurate, however, as the field of medicine (in particular as it applies to diabetes) is rapidly evolving, the information should not be relied upon, as it is designed for informational purposes only. It should not be used in place of medical advice, instruction and/or treatment. If you have specific questions, please consult your doctor or appropriate health care professional.
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