Basal-bolus insulin therapy is an intensive insulin regimen that is usually followed by patients with type I diabetes. This therapy involves taking a shorter-acting insulin (bolus) at mealtimes to compensate for increased blood sugar levels and a longer-acting insulin (basal) during periods of rest such as during sleeping and in-between meals. This therapy attempts to simulate a body’s natural insulin production by the pancreas and ensures consistent blood sugar levels throughout the day.
Bolus insulin refers to rapid-acting or short-acting insulin that is taken specifically during mealtimes to reduce blood sugar levels immediately following a meal. Patients can either follow a fixed or flexible schedule. In a fixed schedule, patients take the same amount of their bolus dose after each meal regardless of blood sugar levels or carbohydrate intake. In a flexible schedule, the dosage of bolus insulin is decided depending on the carbohydrate intake, level of physical activity, blood sugar levels, and other factors such as illness.
There are 2 main types of Bolus insulin
- Rapid-acting Insulin
Rapid-acting insulin has an estimated onset of action of 15 minutes after administering the dose. It reaches peak activity in 1-2 hours and the overall effect lasts between 4-6 hours. Because of its short duration of action, it reduces the risk of hypoglycemia in patients and is usually preferred over regular insulin. A rapid-acting insulin is essentially an insulin analog that is developed to replicate the natural meal-induced insulin secretion by the pancreas.
- Short-acting or regular insulin
Short-acting or regular insulin is similar to rapid-acting insulin, however, has an onset of action about 30 minutes after administration. It reaches peak in about 2-4 hours and has a duration of action lasting up to 8 hours.
Basal insulin refers to a longer-acting insulin that is usually taken once or twice a day. It is used to maintain blood sugar levels during sleep, periods of fasting, and in-between meals. It is also known as ‘background’ insulin, as it maintains adequate blood sugar levels during periods of rest.
There are 3 main types of Basal insulin.
- Intermediate-acting insulin
This insulin is absorbed more slowly and lasts a long time. Its onset of action is usually in about 1-2 hours. It reaches peak activity in 4-6 hours and its effect lasts for about 12 hours. It is usually taken twice a day, often at bedtime and in the morning. The only intermediate-acting insulin available is called NPH insulin (Humulin N, Novolin N) which is an isophane suspension of human insulin. It has a cloudy consistency because of insulin crystals in the solution.
- Long-acting Insulin
Detemir (Levemir) and glargine (Lantus, Basaglar). This insulin reaches the bloodstream several hours after injection and the effect lasts for up to 24 hours. Because of the longer duration of action, they may be taken only once a day.
- Ultra-long acting Insulin
Glargine u-300 (Toujeo) and Degludec (Tresiba). Ultra-long-acting insulin reaches the bloodstream in about 6 hours after administration of the dose. It lasts for about 36 hours and is taken once a day.
Advantages of the Basal-Bolus therapy
- Gives flexibility in choosing meal times. This might be beneficial for people who do shift work.
- Since the Bolus insulin dosage can be controlled, it allows for more flexibility over the amount of carbohydrates and sugars ingested during meals and snacks.
- Changes in physical activities such as exercise or fasting can easily be accommodated while maintaining blood sugar levels.
- Allows for a more flexible lifestyle.
- Newer devices such as Insulin pumps are now available which can be programmed to deliver both basal and bolus doses. This eliminates the need for taking multiple injections.
- Some studies have even shown lower blood sugar levels over the course of this therapy.
Disadvantages of Basal-Bolus therapy
- One of the major disadvantages of this therapy is that it involves taking multiple injections (4 to 6) throughout the day. This might be difficult for some patients, especially children.
- Blood sugar levels need to be checked several times throughout the day.
- Close monitoring of carbohydrate intake and physical activity is needed.
- You need to be able to adjust the insulin dosage on a daily basis depending on varying factors such as activity level.
- Hypoglycemia is a common side effect and patients need to be aware of the amount of dosage taken before each meal. A rapid-acting source of sugar and a blood testing kit needs to be carried out every day to prevent hypoglycemia.
- Other side effects may include weight gain or allergic reactions at the injection site.
Delivery of Insulin
- Insulin syringes
The most common method of delivery is a subcutaneous injection via syringes. They are available in different sizes and needle lengths.
- Insulin pens
Insulin pens make the delivery of insulin easier and consist of a cartridge containing insulin. There are 2 different types available, reusable and disposable. The insulin dosage is pre-measured in both types which makes it convenient to use. This method is often preferred as it’s less painful than the syringes and eliminates the need to carry insulin bottles and syringes.
- Insulin pumps
Insulin pumps are small computerized devices that can be programmed to deliver both ‘basal’ and ‘bolus’ doses. It delivers small amounts of insulin throughout the day and a bolus dose during meal times. Some are programmed to check the blood sugar levels before each meal and adjust the bolus dose accordingly. It consists of a reservoir, a pump, and an infusion set. The reservoir holds the insulin cartridge and the pump is a device that is worn outside on the body. The infusion set contains a short thin tube (cannula) that delivers insulin and is placed under the skin. Although insulin pumps are convenient, they are expensive and take some time to get used to.
Basal-Bolus therapy in Type II diabetic patients
Although the Basal-Bolus therapy is recommended in adults with Type I diabetes, it can also be used for diabetic management of patients with Type II diabetes. Type II diabetic patients usually produce adequate amounts of insulin, but it can be used in patients experiencing high blood sugar levels, especially after meals. It is also an effective way to control diabetes in patients who are hospitalized.
Basal-Bolus therapy is one of the most effective ways of managing diabetes, especially in Type I adult diabetic patients, as it mimics the natural body’s response to increased blood sugar levels and maintains it at stable levels to ensure quality of life.