Basal-Bolus Insulin Therapy for Type 1 Diabetes

There is no “one size fits all” approach for treating type 1 diabetes. It’s important to find the most suitable program that fits in with your eating and sleeping routines and activity levels.

Which insulin therapy is right for you?

Every therapy for type 1 diabetes features a base or “basal” form of insulin. Having enough basal insulin throughout the day gives your cells a steady level of sugar for energy. Without it, your blood sugar and ketones could rise, leading to a potentially fatal condition known as diabetic ketoacidosis.

The amount of basal insulin each person needs varies, but typically demand will be greatest early in the morning owing to physical activity during the day. There are several types of basal insulin available, with different coverage.

Types of Basal-Bolus insulin

1. Intermediate-acting insulin can be taken 1-2 times a day, and works after 1–3 hours, peaking between 4-8 hours after injection. Intermediate-acting insulin fades around 12–24 hours following injection. If taken at breakfast, it can cover your blood sugar requirements over lunch. However, this approach may prove unpredictable and unreliable, especially if lunch is delayed and blood sugar levels start to drop.
2. Long-acting insulin is injected once a day and provides coverage for around 24 hours. Insulin pumps give rapid-acting insulin in short bursts every couple minutes, and may be fine-tuned according to your body’s specific insulin needs.
3. Insulin “boluses” supplement basal insulin to manage spikes in blood sugar that occur after meals. Mealtime insulin doses can be timed to treat peaks in blood sugar levels after eating carbohydrates (starches and sugars), typically around 30-90 minutes after you eat.
4. Rapid-acting insulin is also ideal for mealtimes since it takes only 5–15 minutes to work, and peaks after 30-90 minutes. Unlike short-acting insulin—which peaks 1-4 hours after injection and can remain in your body for up to six hours—rapid-acting insulin analogs do not stay in the bloodstream, thereby reducing the risk of low blood sugar (hypoglycaemia). But short-acting or “regular” insulin is often the preferred form of insulin if you are consuming a large meal or a meal with a high-fat content that would likely raise blood sugar levels for several hours.

Every kind of insulin comes with pros and cons. Choosing the program that is right for you can pose a challenge. Here are some sample plans that may work for you:

Plan A

• Rapid- plus intermediate-acting insulin taken at breakfast and dinner

This simple two-injection program is not suitable if you need flexibility around mealtimes and the amount of carbohydrates consumed. Taking a high morning dose of intermediate-acting insulin may cause your blood sugar to drop around lunchtime if you have been active or if you eat later than scheduled. You also risk a blood sugar spike by late afternoon or a “crash” at night at the peak of your evening dose.

Plan B

• Rapid- plus intermediate-acting insulin at breakfast
• Rapid-acting insulin taken at dinner
• Intermediate-acting insulin taken at bedtime

This program alleviates the evening crash with a further intermediate-acting dose given at bedtime. The morning dose of intermediate-acting insulin may still cause a drop in blood sugar before lunch and an afternoon spike after the morning dose wears off.

It may be necessary to schedule exercise around doses and eat a consistent level of carbohydrates at lunch to avoid drops in sugar.

Plan C

• Rapid-acting insulin taken at breakfast, lunch, dinner, and snack time
• Intermediate-acting insulin taken at bedtime

With the insulin coverage spread throughout the day, your blood sugar levels will be stable, allowing for more flexibility in mealtimes. However, this program involves a high level of maintenance with multiple injections and “top ups” with each snack and activity. And you may be at risk of a blood sugar “crash” in the afternoon or evening if the intermediate- or long-acting insulin fails to last a full 24 hours.

Plan D

• Rapid-acting insulin taken at breakfast, lunch, dinner and snack time
• Long-acting insulin taken at same time once a day

Like Plan C, this program provides a lasting, consistent insulin coverage but with frequent injections, given separately.

Long-acting insulin taken once a day also allows maximum flexibility in terms of mealtimes and activity levels. Drops may still occur in the middle of the day, when basal insulin is at its lowest.

Plan E

• Insulin taken via a pump

Small insulin pumps deliver programmable bursts of rapid-acting insulin via a soft plastic tube called an “infusion set” inserted just under the skin, giving coverage throughout the day and night at the touch of a button. Even though the basal insulin dose is fairly accurate (doses can be given in tenths or even twentieths of a unit and staggered throughout a large or high-fat meal), the infusion set must be changed every few days in order to avoid infection.

The convenient pump gives you ultimate freedom in terms of eating, exercise and sleeping routines. You can even pre-set the pump to take into account for particular circumstances that may increase your blood sugar levels, such as menstruation, pregnancy, stress, illness, or intense exercise.

Unfortunately pumps are expensive and may not be covered under all health insurance plans. Using a pump correctly and achieving ideal blood sugar levels can prove challenging initially. Though discreet, you may find wearing the pump painful or embarrassing. Additionally, there is the risk that a programming mistake could lead to ketoacidosis or a complication such as a kink in the pump. Having said that, experienced users enjoy a flexible lifestyle and are less likely than other insulin users to experience hypoglycemic episodes.

The right treatment program to treat type 1 diabetes depends on many variables, including lifestyle, practicality, and cost. Your doctor can help you come up with the plan that offers the best blood sugar control with the least amount of inconvenience.