Basal Importance for Great Control

Why basal is the most important component of T1D management

Basal (or long-acting) insulin is designed to keep your blood sugars stable at one level on a typical day, without any food interference. Your needs change depending on the amount of exercise you do in a day and the total amount of food you eat.

Getting good blood sugar control is absolutely impossible without a correct basal dose/rate. If your basal dose is too low, you will end up overcorrecting with bolus, and then be low and end up on the ‘diabetic rollercoaster’. The same is for a high basal dose: your blood sugars will be going low the whole time and you are likely to get frustrated and overeat at a certain point. Both mean, at the end, that you will end up over-consuming calories and slowing down your fat loss and progress.

Getting the basal right is also important for performance in training and exercise. When you have a high dose, any activity will very quickly drop your blood sugars very low and you will be forced to stop the workout. They will also be much harder to bring up into a safe range.

Not enough basal will cause you to raise a lot during resistance and HIIT workouts, which means that your body will be using its own muscle tissue to fuel the activity. In this case, you will lose muscle mass, which you need to be building up to achieve increased insulin sensitivity and your desired body shape.

How basal actually works, how a pump can replace basal

Common long-acting (basal) brand names: Levemir, Lantus, Toujeo, Tresiba, Basaglar.

Basal insulin is injected into the subcutaneous tissue (under the skin), just like the fast-acting insulins. Basal is crystalized underneath the skin and is absorbed by the body at a certain rate throughout the day. The absorption rate depends on the injected dose and the type of insulin used. Usually, the lower the dose, the faster it is absorbed and the faster it runs out.

Lower insulin dose = Faster absorption time

Higher insulin dose = Longer absorption time

For users of pumps, there is a basal rate that can be set for each hour of the day. Instead of another type of insulin, the pump uses short acting insulin as basal. This allows pump users to tailor the delivery of basal insulin to different parts of the day, turn the delivery off for activity and increase basal rates to accommodate high-fat or high-carb meals and to be much more flexible with their day-to-day control.

Testing basal rates, why carb free and fasting do not work

Our bodies are ever-changing and no single day will be the exact same as the day before. Often, our basal needs will be very different on different days.

If you are an individual with a highly varied schedule, then basal testing, which all doctors and nurses love to recommend, may as well not work for you. Here are some reasons why:

  • On days you are more active, you insulin sensitivity will rise you will need less basal

  • On days you consume more food in total, you insulin resistance will go up and you will need more basal

  • When fasting, the body may need less basal insulin, as some of the basal is used to help accommodate for the food

  • Carb free meals do not work, as protein and fats also have a significant effect on blood sugars (individuals on Keto may need to inject up to 5 units just for a completely protein meal)

The way to understand your basal is to look at you blood sugars on a typical day for you and see if you are correcting a lot with short-acting insulin in between meals or if you are treating too may lows. Beware, that if the low is due to an earlier correction of a high, it IS NOT an indication that your basal is too high, in fact the opposite, it is likely to be too low, as you were going high at first. You need to see repeating patterns before drawing any conclusions.


Basal is the crucial element of diabetes management, and getting it correct is the only way to gain control and succeed in your diabetes and fitness goals. Getting the correct dose requires observation, and experimentation. You may have different needs of basal on different days, and you will need to set different amounts of basal insulin to accommodate for those needs.


Disclaimer: No information on this blog can be considered advice medical or otherwise. It is my own experience and findings. Do not make any changes to your care without getting professional medical advice.

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