Insulin Pump Therapy: Advanced Bolus Options

An insulin bolus is the insulin given to cover your food. The types of meals which you eat can have varying effects on your blood glucose levels and this can differ between individuals. An insulin pump allows a number of different bolus options for your meals.

By learning the different types of bolus options, this will allow you to optimise your diabetes control by matching the insulin delivery to the effect the meal has on your blood glucose levels.

Considering both the timing of your meal bolus and the type of food, can help you to control your blood glucose level. An advanced bolus option may also be useful.

There are three different types of bolus options available. The names may vary depending on which insulin pump you are using.

Normal/Standard Bolus (Single, short bolus)

A normal bolus is the most common type of bolus and you will likely use this most often for your food.

This is delivered similar to an injection of rapid acting insulin where you have the total amount of insulin for the food before your meal (usually 10-15mins).

Dual/Extended Bolus

This type of bolus is a combination bolus, where part of the bolus is delivered as a normal bolus immediately prior to the food and the remainder of the bolus is delivered slowly over a set period of time.

Example

50% normal bolus
50% extended over 2 hours

There are two steps to this bolus:

Choose how much insulin is given up front (remaining insulin will be given over an extended time).
How long would you like to extend the bolus for?

Square/Extended Bolus

This type of bolus is where the bolus delivery is extended over a set period of time. No immediate bolus is
given. This type of bolus is less commonly used.

The Glycaemic Index (GI)

All carbohydrate eaten will break down into glucose but not at the same rate and this will have different effects on your blood glucose (the sugar your body makes from the food you eat). The glycaemic index (GI) is a guide to how carbohydrate foods affect your blood glucose levels. The GI of glucose is 100 as it is absorbed rapidly.

A high GI food (more than 70) increases the blood glucose levels quickly for a shorter amount of time, whereas low GI food (less than 55) results in a slower and more prolonged rise in blood glucose level.

Two meals with the same carbohydrate content can affect your blood glucose levels differently depending on their GI. It is important to remember that not all low GI are healthy and not all high GI foods are unhealthy.

Low GI Examples:

Porridge oats, multigrain/seeded bread, basmati rice, sweet potatoes, pasta, lentils and pulses.

High GI Examples:

white bread, mashed potatoes, cornflakes, rice krispies, jam and fruit juice.

Often meal choices contain a combination of low GI and high GI foods where the overall effect may result in a medium GI. As well as GI there are several other factors which effect how quickly the carbohydrates you eat changes to glucose in your blood. This includes:

Meal size	large amount of any type of carbohydrate will take longer to digest than a smaller amount. You may find an advanced (split) bolus useful for meals over a certain size (consider meals over ______g).
Fat and protein	Having high fat foods (oil, butter, cream, cheese etc.) and high protein foods (meat, fish, eggs etc.) as part of a meal, will slow down the rate of digestion therefore lowering the GI of the meal.
Fibre	High fibre foods such as whole grain cereal or bread, fruit, vegetables, beans or pulses and potato skins, are digested very slowly and generally have a lower GI.
Processing	A more processed food is likely to have a higher GI. For example, easy cook rice has a higher GI than basmati rice. Whole oats have a lower GI than instant porridge due to processing methods.
Cooking Method	‘Al dente’ pasta will have a lower GI value when compared to overcooked pasta.
Ripeness	Well ripened fruits will have a higher GI value as the sugar is more readily available.

When/how should I use an Advanced Bolus?

If a normal bolus is working there’s no need to try a different type. If you have found a normal bolus unsuccessful in managing your blood glucose levels after eating, then you should try a different bolus option. Everyone is individual and will respond differently.

We would normally suggest starting with a dual-wave/extended bolus and using a 50:50 split. So deliver 50% of the bolus 10-15 minutes before the meal and 50% 2 hours later. If this doesn’t work, then it may need some adjustment to the duration or to the split. Try again until you find what works for you.

Remember to keep a note of this for future reference.

(It’s a good idea to check your blood glucose levels every hour or review your sensor data when trying out a new bolus option-so you can see the effect it is having).

If glucose is dropping soon after eating this indicates a smaller proportion of the bolus is required before the meal (e.g. try 40:60, 30:70).

If glucose is rising soon after eating, this indicates a larger proportion of the bolus is required before the meal (e.g. 60:40, 70:30).

If glucose remains high 2-3 hours after eating, this indicates the bolus needs extended over a longer period of time (e.g. extended by further 30mins as required).

What do I do if I decide to have more food while the bolus is running?

You can deliver a normal/standard bolus for extra foods (e.g. additional course/snack) while an advanced bolus is running (although not recommended if you are testing the bolus).

How do I check if the bolus is working?

If you have used a normal/standard bolus, check your blood glucose levels/sensor data after 2 hours (it should not have risen by more than 2mmol/l from your pre-meal reading).
If you have used an advanced bolus, check your blood glucose levels/sensor data every hour for the
duration of the bolus.
If necessary you can stop the bolus. Make sure you know how to do this on your pump.
If you are unwell or have been active it will be difficult to assess if the bolus has worked for you.

What about Fats and Protein?

Recent research suggests the need for extra insulin if eating large quantities of fat or protein. In large quantities protein may be converted into glucose over a prolonged time (usually 4-12 hours). A moderate portion of protein is about the size of a deck of cards and should not require any extra insulin when eaten in this quantity.

If an advanced bolus is not successful in preventing post-meal rises following a high fat and / or protein meal, you may wish to try taking some additional insulin. This would be best discussed with your diabetes dietitian.

Insulin Pump Therapy: Advanced Bolus Options

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