Did You Know?
According to the American Diabetes Association, every 17 seconds someone in the U.S. is diagnosed with diabetes.
Insulin therapy is the first line of treatment for people with diabetes. Be it type 1 diabetes (insulin deficiency) or type 2 diabetes (body does not respond to insulin), taking insulin shots is necessary to control high blood sugar levels. However, there are different types of insulin, each one formulated to regulate blood sugar levels in a unique way. Individual factors, such as the amount of time taken for insulin to get absorbed, and lifestyle choices that include diet and amount of exercise done everyday, are considered before prescribing a specific type of insulin.

Following are the main factors used to classify insulin given to diabetic patients.

Onset: It is the amount of time insulin takes to begin lowering blood sugar. Simply put, onset time indicates how fast the action of insulin begins to take effect after administration.

Peak: It refers to the length of time insulin is most effective in reducing blood sugar. In simple words, it indicates how long insulin works at its maximum effectiveness.

Duration: The length of time insulin is found to be effective in lowering blood sugar. It is the time during which insulin works to reduce blood sugar.

Insulin Types

Depending upon these factors, following are the types of insulin recommended for the treatment of diabetes.

Rapid-acting Insulin
Brand NameOnsetPeakDuration
NovoLog or aspart15-30 min.30-90 min.3-5 hours
Apidra or glulisine10-20 min.40-50 min.3-5 hours
Humalog or lispro20-30 min.30-90 min.1-2½ hours

Also referred to as mealtime insulin, rapid or fast-acting insulin is usually given a few minutes before having a meal. As we all know, the blood sugar level increases rapidly after meals. Rapid-acting insulin that starts working quickly and helps to prevent spikes in blood sugar. As this type of insulin starts to take effect quickly, it can increase the risk of hypoglycemia if proper dosage is not followed. It may be administered under proper medical supervision to keep a check on blood sugar levels. The insulin gets absorbed and acts very quickly; hence can also be administered immediately after a meal. Rapid-acting insulin is usually recommended for patients suffering from type 1 diabetes. However, in some instances, they may be recommended for people with type 2 diabetes.

Short-acting Insulin
Brand NameOnsetPeakDuration
Humulin R or Novolin R (regular)30-60 min.2-5 hours5-8 hours

Unlike rapid-acting insulin, short-acting insulin does not have a rapid onset of action. Also referred to as neutral or regular insulin, it is often administered 30 -60 minutes prior to a meal. Although, it does not act as quickly as rapid-acting insulin, the patient must ensure that he/she has something after taking a dose of short-acting insulin, or else it may cause a drastic fall in blood sugar levels and increase the risk of hypoglycemia. One benefit of using short-acting insulin is that one does not have to take it every time before a meal. In most cases, it is mixed with long-acting insulin and administered twice a day to control blood sugar throughout the day.

Long-acting Insulin
Brand NameOnsetPeakDuration
Lantus or glargine1-1½ hoursPeakless20-24 hours
Levemir or detemir1-2 hoursNo peak timeUp to 24 hours

The main advantage of using long-acting insulin is that the effect lasts for the entire duration of 24 hours. The absence of peak activity is the hallmark of this type of insulin. Long-acting insulin is released at a consistent rate, which guarantees that its effectiveness lasts for a longer duration.

Intermediate-acting Insulin
Brand NameOnsetPeakDuration
Humulin N, Novolin N or NPH (N)1-2 hours4-12 hours18-24 hours

Intermediate-acting insulin is formulated to be effective for several hours after being administered. As it is slowly released into the body, the effect of this type of insulin lasts for a long duration. It is able to maintain its effect longer than both short- and rapid-acting insulin. Intermediate-acting insulin often contains a retarding substance, which ensures that it does not get absorbed rapidly. It often acts as basal or background insulin; meaning, it tends to work for a 24-hour period, regardless of food intake. This type of insulin is often mixed with short-acting insulin to regulate blood sugar levels at night.

Combination Insulin
Brand NameOnsetPeakDuration
Humulin 70/3030 min.2-4 hours14-24 hours
Novolin 70/3030 min.2-12 hoursUp to 24 hours
Novolog 70/3010-20 min.1-4 hoursUp to 24 hours
Humulin 50/5030 min.2-5 hours18-24 hours
Humalog Mix 75/2515 min.30 min.- 2½ hours16-20 hours

Combination insulin is a mix of two different types of insulin. The insulin formula is a combination of intermediate-acting insulin and a rapid- or short-acting insulin. Its usage accounts for around 40% of people diagnosed with type 2 diabetes. Depending upon the proportion of combination in the insulin products, there are different types of insulin. Premixed doses are available in the ratio of 70:30, 50:50, and 75:25, and are injected twice or thrice during the day before having a meal.

Insulin Concentration

Insulin formulations that are dissolved in liquids, come in different concentrations. The standard insulin concentration in the United States is U-100, which indicates that there are 100 units of insulin in every milliliter of fluid. Higher strength insulin, such as U-500, are also available and prescribed in people with severe insulin resistance. In some countries, U-40 strength insulin are also available. Syringe size will vary depending on the insulin strength that is prescribed for treatment. So, patients have to ensure that the syringe size matches with the concentration of insulin recommended.

Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.