What is basal insulin?

Basal insulin refers to long-acting insulin that works to control blood sugar over a 24-hour time period. Our body requires insulin so as to regulate the amount of blood glucose after eating. Basal insulin stabilizes blood glucose levels during periods where you’re not eating, such as when you sleep. During these “fasting” periods, the liver secretes glucose into the bloodstream, which basal insulin helps control. By regulating the rate your glucose levels are released, your cells are properly use glucose for energy.

Types of basal insulin

The 3 main types of basal insulin include the following:

Intermediate-acting insulin

Examples of basal insulin that belong to this class include Novolin and Humulin. Intermediate-acting insulins usually take 4 to 8 hours before they peak and can last up to 16 hours. These insulin drugs are supposed to be taken once or twice every day.

Long-acting insulin

Examples of basal insulin that belong to this class include insulin glargine and insulin detemir. When you inject this basal insulin, it starts to work between one and a half hours to 4 hours and can last in your body for up to 24 hours. Long acting basal insulin such as insulin glargine and insulin detemir have a steady work rate.

Ultra-long acting insulin

Tresiba (insulin degludec) is the only basal insulin that belongs to this class of insulin drugs. This basal insulin has the longest duration of 42 hours and has no peak time.


The dosage of basal insulin will vary depending on the class of drugs they belong to. Both insulin glargine and insulin detemir can be injected once or twice daily. If taken once, long-acting insulin should be administered before you go to sleep. If taken twice, it should be take 12 hours after the starting dose. The dosage of insulin detemir and insulin glargine will be based on your results of blood sugar testing, glycemic control goals, and metabolic needs. Insulin degludec should be injected once daily. You should not administer insulin degludec intramuscularly or intravenously. Intermediate-acting insulin such as Humulin and Novolin should be administered before you go to sleep. They can be administered alone or together with short acting insulin.

Disclaimer: Please note that the contents of this community article are strictly for informational purposes and should not be considered as medical advice. This article, and other community articles, are not written or reviewed for medical validity by Canadian Insulin or its staff. All views and opinions expressed by the contributing authors are not endorsed by Canadian Insulin. Always consult a medical professional for medical advice, diagnosis, and treatment.