Insulin is a hormone made in the pancreas that is responsible for regulating blood sugar levels. Diabetes is a condition where the body doesn't make enough insulin or can't use it properly.

People diagnosed with diabetes benefit from increasing their body's natural insulin levels by injecting insulin.

Different types of insulin are available. They can be classed by:

• how quickly they work (onset time)
• how long their effects last (duration)
• when they peak (peak time)

Basal insulin is one type of insulin that is available, and it plays a vital role in managing diabetes.

What is basal insulin?

Basal insulin is also known as background insulin. It helps to keep blood sugar levels stable during periods of fasting, such as between meals or during sleep.

During these times, the body keeps releasing sugar (also known as glucose) into the bloodstream. This gives energy to the body's cells.

Basal insulin helps to keep levels of this glucose in check. The insulin reaches the bloodstream several hours after injection.

It keeps glucose levels constant throughout the day and night. In general, basal insulin remains in the system for 18-24 hours.

Types of basal insulin

There are two main types of basal insulin:

Long-acting insulin

This type of insulin may be recommended for several types of diabetes. It generally acts in the body for up to 24 hours, although some types can last longer than this.

Depending on the type of insulin used and patient needs, long-acting basal insulin should be injected either once or twice daily.

Long-acting insulin tends to have no peak activity and mimics the natural function of the pancreas. It allows for consistent delivery, keeping blood sugar levels steady throughout the day and night.

The three types of long-acting insulin are:

Glargine

• provides consistent activity from around 1 hour after injection
• works for up to 24 hours
• usually injected once daily

Detemir

• provides consistent activity from within 1 hour after injection
• usually does not last the full 24 hours
• 1-2 shots required daily

Degludec

• provides consistent activity for more than 42 hours
• allows for a more flexible injection schedule

Intermediate-acting insulin

This is used in the same way as long-acting insulin, but generally needs to be injected twice daily. Intermediate-acting insulin is also known as "isophane" or "NPH" insulin.

It reaches the bloodstream within 2 to 4 hours of injection, and peaks 4 to 12 hours later. Levels start to reduce in the body after this.

Intermediate-acting insulin is often combined with short-acting or regular insulin. This can be done in various ratios as part of diabetes treatment plan prescribed by a doctor.

Other types of insulin

Basal insulin is just one type of insulin. The other types of insulin that can help manage symptoms of diabetes are:

Rapid-acting insulin

This begins to act within 15 minutes of administration and peaks at around 1 hour. Rapid-acting insulin may remain in the body for up to 4 hours. Types of rapid-acting insulin are:

• lispro
• glulisine
• aspart

Short-acting or regular insulin

Short-acting or regular insulin begins to take effect in 30 minutes. It peaks in approximately 2 to 4 hours. Types of regular insulin are:

• humulin R
• novolin R

Advantages and disadvantages

Basal insulin has a number of benefits for those with diabetes, including:

• Easier blood sugar level management: levels remain more even, as it has no peak time.
• More flexible lifestyle: meal and injection timing can be varied, as it has no peak time.
• Less frequent injections: basal insulin only requires one to two injections per day.
• Lower risk of complications: if used soon after diagnosis, according some research.
• Less weight gain: research suggests basal insulin causes less weight gain than other insulin.
• Used as part of a basal-bolus regimen: with an extra shot of bolus insulin at meal times.

Basal insulin is central to many types of insulin therapy and offers many benefits. However, there are some disadvantages to using it, including:

• Hypoglycemia: a common side effect of any insulin. The risk of this is lowest with basal insulin.
• Night-time hypoglycemia: a possibility when using intermediate-acting insulin.
• Weight gain: there's the potential to gain weight, although less so with basal insulin than others.

Dosage

There are many factors to consider when deciding when and how often to use basal insulin. These include:

• lifestyle
• the body's insulin needs
• willingness to inject
• morning blood sugar levels

How basal insulin is used is based on an individual person's needs and the type of diabetes they have. It is always important to discuss these factors with a doctor and stick to the advice they provide.

Type 1 diabetes

People with type 1 diabetes tend to require much less insulin. However, this condition means they need to replace all of the body's insulin.

As such, people with type 1 diabetes should get their dose through an insulin pump or a basal-bolus regimen.

Type 2 diabetes

Those with type 2 diabetes often require more insulin. This is because they are insulin resistant.

A basal insulin program is usually recommended for these people once oral medications are no longer sufficient. This is based on the individual's weight, hormone levels, and diet.

If symptoms cannot be controlled with this method then a basal-bolus regimen may be put in place instead. As basal insulin needs vary from person to person, it is important to stick to the treatment plan outlined by the doctor.