What is a Pre-Bolus?
Pre-bolusing insulin is when you take insulin at a set timeframe before eating, giving the insulin time to become "active" and combat the blood sugar rise.
Pre-bolusing takes some practice, and there are variables to contend with that influence outcomes, like a delayed meal, a child who refuses to eat, or a low blood sugar before a meal. But practice makes perfect, and even with some variables in play, pre-bolusing can help improve overall blood sugar control. According to a study from 2010, “A bolus of rapid-acting insulin 20 min prior to a meal results in significantly better postprandial glucose control than when the meal insulin bolus is given just prior to the meal or 20 min after meal initiation."
If you find that your blood sugar is spiking after your meal, you may need to pre-bolus a little bit earlier. And if you're dropping after meals instead, you may need to pre-bolus a little later. Finding the right balance for your pre-bolus takes some trial-and-error; be sure to connect with your healthcare team to help fine tune your approach.
Note: If you're dealing with delayed stomach emptying (gastroparesis), or hypoglycemia unawareness (not detecting low blood sugar symptoms), definitely talk with your doctor before making changes to your insulin doses or regimen.
Tips for Pre-Bolusing
- Trial and Error - Finding the right timing for your pre-bolus takes some experimentation and patience. Document your trials and learn from the data.
- Look for Patterns - Are your post-prandial blood sugars spiking up high after a meal? You may need to pre-bolus a little earlier. Is your blood sugar going low after a meal? You may be bolusing too early.
- Make Sure Your Ratios Are Right - Fine tune your insulin-to-carb ratios and also your sensitivity factor so that you can pre-bolus with precision and confidence.
- Ask Your Diabetes Team - Do you need more help with the timing of your insulin doses? Check in with your diabetes care team for their guidance and advice.
- Timing of meal insulin boluses to achieve optimal postprandial glycemic control in patients with type 1 diabetes
- Assessment of optimal insulin administration timing for standard carbohydrates rich meals using continuous glucose monitoring in children with type 1 diabetes-crossover randomized study (PDF)