Insulin therapy is required for individuals with diabetes. In a non-diabetic person, the pancreas secretes insulin throughout the day which helps cells absorb and use glucose in the blood for energy. People living with diabetes, especially type 1, make little to no insulin and require injections to facilitate blood glucose usage. Insulin is available in different forms which act differently, lowering the blood sugar at different times, says the National Institute of Diabetes and Digestive and Kidney Diseases.
Rapid Acting
Rapid acting insulin, such as Novolog and Humalog, are injected immediately before meals. According to Life Clinic, they begin to work within five to 15 minutes. Patients should eat meals within this time frame to avoid experiencing hypoglycemia, or low blood sugar. Rapid acting insulin formulations work their hardest or peak, within 30 to 90 minutes after injection and last a total of three to five hours.
Short Acting
Short acting insulin is similar to rapid acting insulin, except it doesn't work quite as quickly. Humulin R and Novolin R are examples of this type of insulin, and may also be referred to regular insulin, notes MayoClinic.com. Short acting, or regular insulin, takes effect in 30 minutes to one hour, requiring a little more mealtime scheduling. They peak within 2 to 4 hours and have an overall duration of 3 to 8 hours.
Intermediate Acting
Intermediate acting insulin, also referred to as NPH insulin, maintains blood sugar control over longer periods of time. Dosage depends on the individual's blood sugar, says Drugs.com. Physicians may instruct patients to mix intermediate acting insulin with other types for better blood sugar control. Humulin N and Novolin N are two types of insulin in this category. Intermediate acting insulin begins to work in one to three hours, peaks in eight hours and may last up to 16 hours, as noted by the National Institute of Diabetes and Digestive and Kidney Diseases.
Long Acting
Long-acting insulin works to maintain steady blood sugar control over the course of 24 hours. Lantus and Levemir are long acting insulin formulations which have an onset of anywhere from one to 10 hours, says MayoClinic.com. Due to the nature of this type of insulin, it has no peak because it continuously works to lower and control blood sugar levels in the blood.
