Diabetes is a disease that affects the way the body produces and uses insulin to control blood sugar. Basal-bolus insulin therapy is an option for diabetes management that combines different types of short- and long-acting insulin.
Doctors now call basal-bolus therapy intensive or flexible insulin therapy.
This type of therapy is becoming less and less frequent because around 30–40 percent of people with type 1 diabetes now use an automatic insulin pump and continuous glucose monitoring, which avoids the need for daily injections.
However, switching between basal and bolus insulin doses at strategic times is the foundation for newer, automated diabetes care technologies.
In a healthy person, the pancreas produces enough insulin for the body’s needs, whether it is active, resting, eating, sick, or sleeping.
This means that people without diabetes can eat food at any time of the day without their blood sugar levels changing dramatically.
However, people with diabetes cannot produce or use insulin effectively enough to control blood sugar. People with diabetes can use injections throughout the day to mimic the two types of insulin: Basal and bolus.
Different types of insulin act for different durations and peak at different times.
Basal-bolus insulin therapy is an intensive insulin treatment that involves taking a combination of insulins.
Some people might take only basal, or “background” insulin. This is a long-acting insulin that boosts activity for around 24 hours at a time, but to a lower peak than rapid-, intermediate-, or regular-acting insulin.
Basal provides a constant supply of insulin to bring down high resting blood glucose levels.
Bolus insulin, on the other hand, has a much more powerful but shorter-lived effect on blood sugar, making it an ideal supplement for people with diabetes to take after meals and in moments of extremely high blood sugar.
A basal-bolus insulin regimen involves a person with diabetes taking both basal and bolus insulin throughout the day.
It offers people a way to control their blood sugar levels without needing to eat meals at specific times each day and helps them achieve similar blood sugar levels to people who do not have diabetes.
There are several advantages to using a basal-bolus insulin regimen. These include flexibility when considering mealtimes and overnight blood sugar control.
This type of treatment might also be helpful for people who work shifts or travel across time zones regularly. Insulin injections generally require specific meal timings, and basal bolus therapy allows a little flexibility.
The downsides to a basal-bolus regimen are that:
- People may need to take and time up to 4 injections a day.
- Adapting to this routine might provide emotional and social challenges, as the timings of injections must be the same each day and this can disrupt routine.
- An injection will also be necessary at every mealtime, which can be difficult to maintain.
- People must always keep a supply of both types of insulin with them.
These factors can make it harder for some people to manage diabetes well.
However, devices are now available that constantly monitor glucose and either automatically administer insulin, serving as an artificial pancreas, or notify the user when to apply shots through a pump.
Some “smart” pumps connect to phone apps to make administration easier; some also record blood glucose data and provide reports directly to the doctor.
For this reason, doctors do not recommend basal-bolus injections as often as they did before. They now tend to focus on devices that provide a better quality of life.
Basal insulin is also sometimes known as “background insulin.”
People usually take basal insulin once or twice a day to keep blood sugar levels consistent.
By keeping sugar levels steady when a person is not eating, basal insulin allows the cells to convert sugar into energy more efficiently.
Examples of long-acting basal insulin for people with diabetes include:
- glargine (Basaglar or Toujeo, which is ultra long-acting)
- detemir (Levemir)
- degludec (Tresiba}
These insulins reach the bloodstream several hours after injection and remain effective for up to 24 hours.
However, people using these treatments will also need to use bolus insulin, or rapid-acting insulin, when they eat. The combination of these insulins is known as basal-bolus therapy.
As well as using long-acting basal insulin, some people with type 2 diabetes may need to take oral, non-insulin medications to measure blood sugar.
Typically, people with diabetes take bolus insulin at meal times to keep blood sugar levels under control after eating.
Bolus insulin needs to act quickly and is known as “rapid-acting” insulin. It works in about 15 minutes, peaks in about 1 hour, and continues to work for 2 to 4 hours.
Rapid-acting insulins include:
- aspart (Novolog)
- lispro (Humalog)
- glulisine (Apidra)
Bolus insulin needs to reflect the amount of food a person eats during a meal. So it is essential that a person with diabetes knows how many carbohydrates they eat so that they can adjust the amount of insulin they need.
Carbohydrate counting and insulin-to-carbohydrate ratios are important tools for people with diabetes who use insulin.
However, some people find it easier to use an “insulin scale” instead.
An insulin scale is a list of recommended amounts of insulin to take before different types of meal.
The scale takes into account pre-meal blood sugar levels and the usual amount of carbohydrate a person would eat during that meal.
However, people using insulin scales still need to consider the dose of insulin they will take. They should compare it to the amount of food they are eating and account for activities planned for after eating.
This is because if they are going to eat more than usual, then they may need more insulin than is listed on the scale. Or, they may need less insulin than is listed on the scale if they are planning on being more active than usual that day.
For example, if a person goes on a run after eating, they will not need as much insulin because the body uses more glucose during exercise.
In recent years, pumps have become widely available for people who need insulin. These are rapidly taking over as the mainstream alternative to insulin injections.
Insulin pumps are computerized devices that provide a steady, measured, and continuous dose of basal insulin, or a surge of bolus insulin at mealtimes.
The pump delivers insulin through a catheter that the person tapes in place on the skin. Typically a person has to wear the pump at all times.
This device can make insulin therapy less disruptive and timing-dependent. However, a person will still have to request that the pump administers bolus insulin after eating a meal.
Insulin pumps can also be quite bulky, and people tend not to wear them during physical activities with reduced or removed clothing, such as swimming or sexual intercourse. Some people also take off the pump while sleeping.
Those using a pump always have the option to swap it for traditional insulin injections. For example, some people choose to leave insulin pumps at home when going on vacation and adopt a basal-bolus injection regimen. Some children choose not to wear it while on break from school over the summer.
Changing from a pump to another way of taking insulin will not affect blood sugar control, so long as a person does not miss any doses.
Basal-bolus insulin therapy involves taking slow-acting insulin to moderate blood glucose when fasting, and short-acting insulin around mealtimes to quickly reduce the impact of dietary glucose.
While people usually inject this type of insulin therapy with a needle and syringe or a pen, insulin pumps work similarly. Today, many people prefer to use these pumps rather than manual injections.
Talk to a doctor about the available options and devices, and see which regimen is the most suitable.