In people without diabetes, insulin is produced by the pancreas to keep the body's blood sugar levels under control throughout the day.
The pancreas produces enough insulin, whether the body is active, resting, eating, sick, or sleeping. This allows people without diabetes to eat food at any time of the day, without their blood sugar levels changing dramatically.
For people with diabetes, this doesn't happen. However, a similar level of blood sugar control can be achieved by injecting insulin.
Injections can be used throughout the day to mimic the two types of insulin: basal and bolus. People without diabetes produce these throughout the day and at mealtimes, respectively.
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What is a basal-bolus insulin regimen?
A basal-bolus insulin regimen involves a person with diabetes taking both basal and bolus insulin throughout the day.
It offers them a way to control their blood sugar levels. It helps achieve levels similar to a person without diabetes.
There are several advantages to using a basal-bolus insulin regimen. These include:
A basal-bolus insulin regimen may help people who do shift work or travel across time zones.
- flexibility as to when to have meals
- control of blood sugar levels overnight
- they are helpful for people who do shift work
- they are helpful if travelling across different time zones
The downsides to a basal-bolus regimen are that:
- people may need to take up to 4 injections a day
- adapting to this routine can be challenging
- it can be hard to remember to take the injections
- it can be hard to time the injections
- it's necessary to keep a supply of insulin with you
These things can make it harder to manage diabetes well. To make it easier, some experts suggest introducing the regimen gradually. When this happens, bolus insulin is taken, beginning with just one meal at a time.
What is basal insulin?
Basal insulin is also sometimes known as "background insulin." It is usually taken once or twice a day to keep blood sugar levels consistent. This is important when the body is releasing glucose to supply cells with energy, during fasting.
By keeping sugar levels steady during fasting, basal insulin allows the cells to change sugar into energy more easily.
Basal insulin makes up about half of the total amount of daily insulin. It is sometimes called "long-acting insulin" because it needs to be effective for a long time.
Examples of long-acting basal insulin for people with diabetes include:
Basal insulin is usually taken once or twice a day to maintain constant blood sugar levels.
- glargine (Lantus)
- detemir (Levemir)
These insulins reach the bloodstream several hours after injection and are effective for up to 24 hours.
However, people using these treatments will also need to use rapid-acting insulin when they eat. This applies for people with type 1 diabetes and those with type 2 diabetes.
As well as using long-acting basal insulin, some people with type 2 diabetes may need to take oral medication. In addition, they may need a weekly injection of a medicine called a "GLP-1 agonist".
What is bolus insulin?
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 so is known as "short-acting" or "rapid-acting" insulin. It works in about 15 minutes, peaks in about 1 hour, and continues to work for 2 to 4 hours.
Brands of rapid-acting bolus insulins include:
Bolus insulin needs to reflect the amount of food eaten during a meal. So, carbohydrate counting and insulin-to-carbohydrate ratios are important tools for people with diabetes who use. However, some people find it easier to use an "insulin scale" instead.
An insulin scale is a list of how much insulin should be given before a meal. It takes into account both the pre-meal blood sugar level and the amount of carbohydrate that would usually be eaten at that meal.
However, it is still important for people using insulin scales to think about the dose of insulin they will take. They should compare it to the amount of food they are eating and what activities they have planned for after they eat.
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.
Alternatives to injections
Insulin for people with diabetes is usually injected. However, in recent years, some alternatives to syringe injections have become available.
One alternative to injections are insertion aids, which are spring-loaded devices with a shielded needle. Insertion aids release insulin at the simple touch of a button.
Infusers are another option. An infuser is a device containing a needle or catheter (a flexible plastic tube) that remains under the skin for up to 72 hours.
When a person needs to administer insulin, they inject the insulin directly into the infuser, rather than into the skin. This method reduces the number of times they would need to insert a needle into their skin.
Yet another method is the use of jet injectors. This does not use needles. Instead, a thin, high-pressure stream of insulin is forced through the skin.
Although jet injectors do not involve needles, the pressure can cause bruising.
Insulin pumps are computerised devices that are worn almost all of the time and provide basal and bolus insulin.
Insulin can also be delivered using insulin pumps. These are small, computerized devices that provide a steady, measured, and continuous dose of basal insulin, or a surge of bolus insulin at mealtimes.
The insulin is delivered through a catheter that is taped in place on the skin. The patient typically wears the pump at all times, unless they are sleeping, swimming, or having sex.