📘 Available insulin types

Rapid-acting insulin analog (e.g. aspart, lispro, glulisine) starts working within 5-15 minutes after injection, reaches maximum effect in 1-2 hours and lasts 4-5 hours [1]. You use it to cover meals and to correct high blood glucose. Long-acting or basal insulin analog (e.g. glargine, detemir) starts working in 1-2 hours and maintains a constant insulin level in the blood for 12-42 hours, depending on type [2].

Rapid insulin tries to mimic the pancreas's response to food, while long-acting insulin replaces the continuous insulin production that your pancreas can no longer make [1]. You need both types of insulin for good control. Long-acting insulin helps you between meals and at night, while rapid insulin manages blood glucose rises when you eat.

For meals you use rapid-acting or ultra-rapid insulin analog. These start working in 5-15 minutes (ultra-rapid 2-4 minutes earlier), so you take them just before the meal if you have good blood glucose [3]. The dose depends on how many carbohydrates you will eat and your insulin-to-carb ratio.

You never use long-acting insulin for meals because it doesn't act fast enough and cannot manage the rapid blood glucose rise after a meal [1]. If you only have regular human insulin, it starts working in 30 minutes, so it must be taken at least 30 minutes before the meal.

Basal insulin is long-acting insulin that maintains stable blood glucose in the absence of meals. You consider it an antidote to the glucose made by the liver. It is taken once a day, usually at approximately the same time [4]. This represents about 50% of your total daily insulin requirement. This percentage can vary greatly though, depending on your particularity.

The time of day for administration is generally not very important. Generally basal insulin is taken in the evening for convenience. Sometimes it is taken in the morning, the idea being that if the duration of action is at the limit of 24 hours, a lower risk of overnight hypoglycemia can be obtained, on the tail of insulin action [2]. It is essential to continue basal insulin even when you are not eating anything.

Yes, although all rapid insulins or all long-acting ones have similar actions, there are subtle differences between various types of insulin in the same category [3]. Ultra-rapid analogs (lispro-aabc and fiasp) enter action faster and have a peak of action approximately 25 minutes earlier compared to classic rapid analogs (lispro, aspart, glulisine). For long-acting insulins, degludec and glargine U300 have a flatter action profile and consequently a lower risk of nocturnal hypoglycemia compared to glargine U100 [2].

Individual differences also matter. Some people absorb a certain brand better or have fewer adverse reactions at the injection site. If you change brands, carefully monitor blood glucose in the first days because you may need small dose adjustments, even if you keep the same insulin category. Prices and availability in pharmacies can also vary between different insulin brands.

Insulin analogs are genetically modified versions of human insulin, created to have new properties [5]. The human insulin molecule is modified by changing some amino acids, which makes the insulin act either faster (rapid analogs) or slower and more steadily (long-acting analogs). These modifications don't affect the ability to lower blood glucose, only the onset, peak and duration of action.

Almost all modern insulins are analogs. Advantages over human insulin include more predictable action, lower risk of hypoglycemia and greater flexibility in meal timing [6]. Analogs are more expensive than human insulin, but are generally fully or at least partially reimbursed for people with type 1 diabetes.

Human insulin has exactly the same structure as insulin naturally produced by the pancreas, being manufactured through genetic engineering using bacteria or yeasts [6]. Regular human insulin acts slower than rapid analogs. Its effect starts in 30 minutes, has a peak at three hours and lasts six hours. NPH (intermediate) human insulin has a peak of action at 4-8 hours and lasts 12-16 hours. NPH insulin is gradually being withdrawn from everyday practice, being replaced by long-acting analogs.

Insulin analogs have slightly modified molecules for superior properties, more predictable absorption and lower risk of hypoglycemia [7]. With human insulin you must be more rigid with meal timing and you need mandatory snacks. Analogs offer much more flexibility at meals. However, human insulin works well, is useful for intravenous administration (e.g. ketoacidosis) and is cheaper.

The choice depends on your lifestyle, meal schedule, physical activity and individual response [4]. Children and adolescents benefit most from analogs due to the unpredictability of meals and activity. The current standard is to combine the slowest analog with the fastest one.

Discuss options with your diabetologist and be prepared for a testing period. Factors such as absorption speed at your injection sites, tendency toward nocturnal hypoglycemia or dawn phenomenon influence the choice [8]. There is no "best" insulin universally. The right one for you is the one that gives you the best control with the fewest hypoglycemias.

Ultra-rapid insulin (fiasp, lispro-aabc) is an improved version of rapid analogs that appears in circulation in just 4-5 minutes and starts working approximately 5 minutes earlier than classic analogs [3]. In fact it contains about the same insulin but with "additives" that accelerate absorption. Sometimes you can administer this type of insulin when you start eating or up to 20 minutes after the start of the meal, thus offering greater flexibility.

It is especially useful for meals with simple carbohydrates that rapidly raise blood glucose, for hyperglycemia corrections or when you don't know exactly how much you will eat [8]. Ultra-rapid analogs are ideal for use in insulin pumps, where rapid response improves postprandial control.

Yes, you can change the insulin type, but the change must be made under medical supervision, with careful monitoring [9]. When you switch, for example, from glargine U100 to glargine U300, the insulin dose will generally increase to achieve the same effect. When transitioning from rapid analogs to ultra-rapid ones, initial doses may be similar. Monitor blood glucose more frequently (7-10 tests/day) in the first two weeks after such a change.

Note any differences in control or possible adverse reactions. Changing basal insulin generally requires more attention because it especially affects blood glucose during the night [4]. Keep a detailed diary and communicate frequently with your doctor.

There is no "best" insulin for everyone [4]. The optimal choice depends on your individual needs, lifestyle and your body's response. For most people with type 1 diabetes, the combination of modern analogs (ultra-rapid + long-acting basal) offers the best glycemic control and quality of life [8].

What matters most is how you use the chosen insulin. You need to have correct timing at meals, precise dose selection and frequent adjustments. A well-educated person can achieve excellent control even with regular human insulin. The same person would do even better with modern treatment though. The best insulin for you is the one that allows you to reach glycemic targets with minimum hypoglycemias and maximum flexibility in daily life.

No, insulin cannot be administered orally, in pill form because it is a protein that is destroyed by digestive juices in the stomach and intestine [10]. There have been many attempts to create oral insulin, but protecting the molecule and predictable absorption remain major challenges. Research continues with special formulations and various encapsulation technologies.

Any "diabetes pills" you see in other patients are for type 2 diabetes and don't contain insulin. They are medications that either stimulate the pancreas to produce more insulin (impossible in type 1), or improve insulin sensitivity. For type 1 diabetes, the only currently available options generally everywhere are subcutaneous injections or insulin pumps. Inhaled insulin exists in the USA, but not yet in Europe [11].