Workbook

When Your BG Is Less Than Target
You might also calculate a BG bolus if your BG is lower than target and you are planning to eat.
In this case, your BG bolus might be a negative number. This number will tell you how much to
reduce your carbohydrate bolus. Basically, you are taking less insulin than you would normally
take for the food you are planning to eat. This is often referred to as a negative correction. See
the following example.
Sample BG Bolus Calculation; BG is below target:
If your ISF is 2.8 mmol/L and your target BG is 6 mmol/L, how much is your
BG bolus if your BG is 4.5 mmol/L?
4.5 mmol/L (BG) - 6 mmol/L (target BG) = -1.5 mmol/L lower than target
-1.5 mmol/L (lower than target) ÷ 2.8 (ISF) = -0.5 units
In the above example, you would subtract 0.50 units from your carbohydrate bolus to get your
bolus total. For example, if your carbohydrate bolus was 4.50 units, you would only bolus 4.0
units (4.50 minus 0.50).
Sometimes, if your BG is lower than your minimum target level. it may be easier to treat the
low BG with carbohydrates as you normally would, rather than calculating a negative correction.
In other words, eat or drink 15 grams of fast acting carbohydrate right away! In this case you
would then just take your usual carbohydrate bolus for the meal. Do not add the carbs you used
to treat the low BG.
Putting It Together
After reviewing this information, you may need to use just one of these bolus formulas, or you
may need to consider them together. Consider the following situations.
• You are eating a meal and your BG is in your target range. Just use the I:C.
• It is several hours after a meal and your BG is high. If you are not planning to eat, just use
the ISF.
• Consider when you last bolused. Is that bolus still working? See Insulin on Board on page 50.
• You are about to eat and your BG is outside your target range. Use both the I:C and ISF
and add (or subtract) the results.
12 My Insulin Pump Workbook Animas UK & Ireland