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Diabetes and Insulin Therapy: Doses, Types, Delivery, and More (2024)

Written by: Mikhail Nilov



Time to read 8 min

Our bodies have intricate mechanisms to  control blood sugar levels throughout the day. When something upsets this balance in blood sugar metabolism, diseases like diabetes mellitus result.


Many people with diabetes need external insulin therapy to regulate their blood glucose levels. Here's what you need to know about how insulin works, its types, doses, and delivery methods.

Insulin Basics: How Does Insulin Work?

2 vials of insulin and a syringe for insulin therapy
2 vials of insulin and a syringe for insulin therapy. Image Source

Insulin is a hormone the body naturally produces in the beta cells of the pancreas. It works in tandem with glucagon to regulate how much glucose remains in your blood after a meal.


The job of the hormone insulin is to open your body's cells to glucose to be used as fuel. Any excess glucose is then transformed in the liver into a complex carbohydrate called glycogen to be used later when needed.


Glucagon does the opposite; it tells the liver to change back the stored glycogen to raise glucose levels in the blood when they're too low.

Why Do Some People With Diabetes Need to Take Insulin?

Diabetes mellitus is a disease that affects the beta cells that produce insulin or insulin receptors in body tissues. Depending on the cause and severity of the disease, the body may not make enough insulin, stop producing it altogether (insulin deficiency), or stop responding to it the correct way (insulin resistance).


People with type 1 diabetes have an autoimmune reaction that destroys beta cells in the pancreas. This causes the body to completely shut down insulin production.

Type 2 diabetes happens when the body's cells become desensitized to the amount of insulin produced or due to the gradual degradation of beta cells. 


Depending on the cause, they may respond to different types of diabetes treatments.


That said, for all patients with type 1 and some patients with type 2 diabetes or gestational diabetes, insulin therapy is crucial for survival. That's because the body relies on external sources of insulin to bring down high blood sugar levels, or else they face an increased risk of complications.

Types of Insulin

There are different types of insulin on the market today. The American Diabetes Association classifies them according to how fast they take to reduce blood sugar levels.

Rapid-Acting Insulin

This type of insulin is taken 15 minutes before a meal. It reaches its peak concentration after 1–2 hours, and its efficacy lasts about 2–4 hours.



  • Insulin Lispro: Admelog, Humalog, Lyumjev

  • Insulin Aspart: Fiasp, NovoLog

  • Insulin Glulisine: Apidra

Short-Acting Insulin (Regular Insulin)

One of the most common types of insulin, short-acting insulin is taken 30 minutes before eating. 


It reaches peak concentration after 2–3 hours and lasts 3–6 hours in the blood.



  • Human Regular Insulin: Humulin R, Novolin R, Velosulin R

Intermediate-Acting Insulin

This type reaches the bloodstream about 2–4 hours after injection. Its concentration peaks between 4 and 12 hours and remains in the blood for 12–18 hours.



  • Neutral Protamine Hagedorn (NPH): Humulin N, Novolin N, ReliOn

Long-Acting Insulin

This type of insulin reaches the blood several hours after being taken and has no peak concentration. It's usually taken once daily to control blood glucose for 24-hour periods.



  • Insulin Detemir: Levemir

  • Insulin Degludec: Tresiba

  • Insulin Glargine: Basaglar, Lantus

Ultra Long-Acting Insulin

Like long-acting insulin, ultra-long-duration insulin controls blood sugar levels for over 24 hours. It has the same composition as long-acting glargine, but the concentration is higher.



  • Insulin Glargine U-300: Toujeo

Premixed Insulin

For patients taking insulin, a mix of two of the types above insulin can be used to stabilize their condition. If a person has trouble drawing the right insulin dose from two vials, they can be prescribed premixed insulin with the correct dosage for their condition.


These usually include longer-acting insulin and rapid or short-acting insulin in various ratios.

Methods of Insulin Delivery

Glucose monitoring
Glucose monitoring. Image Source

Unlike other medications that can be taken orally, insulin is made of protein, so it can't be ingested. That's because it gets broken down by the enzymes in the digestive system and thus loses its efficacy.


This necessitates that the insulin is directly introduced to the bloodstream, which can be achieved by one of the following methods:

Insulin Injection

Injection is the traditional method of insulin delivery and is the most widely used.


You can receive insulin injections using a:

  • Insulin Syringe: This requires measuring the insulin dose and injecting it into the stomach's skin, front or side of the leg, back of the upper arm, or the upper buttocks.

  • Insulin Pen: Similar to a syringe. They can come pre-filled or use cartridges with different insulin types.

  • Needle-Free Insulin Jet Injector: For patients who fear needles but still need insulin injections, a jet injector with a needle-free nozzle delivers the same results as a syringe or pen.


  • The easiest method to learn and master in a short time.

  • Syringes are cheap and can be found almost anywhere.

  • Pens usually have short, thin needles that aren't uncomfortable to use.

  • Needle-free jet injectors are fast and don't hurt like traditional injection methods.


  • A fatty layer or lumps in the subcutaneous tissue can form if you inject insulin at the exact site all the time.

  • Syringes are too noticeable for the comfort of some patients.

  • Pens and jet injectors require frequent cartridge changes, which can get too expensive and might not be covered by insurance.

Insulin Pump

An insulin pump is a small device connected to a tube inserted under the skin. It delivers a stable basal insulin dose throughout the day and extra bolus doses of insulin during mealtime.


A pump mimics how the body naturally controls blood glucose by using only rapid or short-acting insulin. This prevents the drawbacks of using long- or intermediate-acting insulins like severe hypoglycemia (low blood glucose).




  • Needs constant blood sugar monitoring to prevent diabetic ketoacidosis (DKA) if the pump malfunctions.

  • An insulin pump requires information to be inserted throughout the day to manage physical activity, snack, and mealtime insulin doses.

  • Can cause weight gain.

  • Is a constant reminder of having diabetes.

Inhaled Insulin

Unlike an insulin shot, inhaled insulin reaches the bloodstream via the sensitive blood capillaries around your lungs. 


A fine powder of rapid-acting insulin is inhaled through the mouth and absorbed by the lungs, reaching your blood within minutes.



  • Helps control blood sugar right before meals.

  • Simple to use.

  • Discreet to carry around.


  • Provides an inaccurate insulin dose.

  • Patients who smoke or have asthma, COPD, or other respiratory diseases may face severe irritation and bronchospasms.

  • Inhaled insulin causes several drug interactions.

  • Patients with type 1 diabetes still need long-acting insulins to control basal insulin levels.

Insulin Dose Calculation

Nugen’s InsuJet Needle-Free Device
Nugen’s InsuJet Needle-Free Device

The dose of insulin you need at each mealtime is determined by your doctor based on your weight, how much insulin your body is producing, and your insulin sensitivity. It also depends on the type, or types, of insulin you're using.


That said, if you need help measuring a single dose for a meal, there are ways to calculate the insulin amount you need if you're using rapid-acting insulin.


  • Carbohydrate coverage insulin is measured according to this equation: 


    Total grams of carbohydrates in the meal ÷ Grams of carbohydrates disposed of by 1 unit of insulin = Carb coverage insulin dose. 

    For example, if you eat 30 grams of carbs in a meal and 1 unit of insulin covers 10 grams of carbs, you must inject 3 units of insulin.


  • High blood glucose correction insulin dose is measured according to this equation: 


    (Actual blood sugar - Target blood sugar) ÷ Correction factor = High blood sugar correction dose 

    That means if your blood sugar is 220 and your target blood sugar is 120, the difference is 100. Divide that by the correction factor (50 for rapid-acting insulin), and you get 2 units of insulin.

    Carb coverage dose + High blood sugar correction dose = Actual bolus dose for mealtime 

    In the previous example, the correct insulin dose at mealtime is: 3 units + 2 units = 5 units of rapid-acting insulin.


Another equation used to determine the amount of insulin you need in total (both basal and bolus) is as follows:


  • If measured in pounds: Body weight in lbs. ÷ 4 = Total daily insulin requirement

  • If measured in kilograms: Body weight in kg. x 0.55 = Total daily insulin requirement

Remember that this calculation might not be suitable for your particular needs. If you're newly diagnosed, and your body still produces insulin, this might be too much. 


Inversely, if you have lower insulin sensitivity, the dosage may be too low for you.

Non-Insulin Diabetes Treatments

Patients with type 2 diabetes who don't have insulin deficiency but are losing insulin sensitivity can benefit from treatment options other than insulin therapy. 


These are usually oral medications or injections that have different action mechanisms. 


They include:


  1. Thiazolidinediones (glitazones): Oral treatment that increases glucose absorption in the body cells.

  2. Incretin-based therapies: Oral/injection treatment that slows down food absorption and glycogen to glucose breakdown.

  3. Insulin-releasing pills (secretagogues): Oral treatment that enhances insulin secretion from the pancreas.

  4. Metformin: Oral treatment that reduces glycogen to glucose breakdown.

  5. Amylin analogs: Injection treatment that slows down food absorption and glycogen to glucose breakdown.

  6. Starch blockers: Oral treatment that reduces carbohydrate absorption in the digestive tract.

Do I Need to Monitor My Blood Glucose Levels?

Glucose monitoring
Glucose monitoring. Image Source

Monitoring your blood sugar levels is crucial to diabetes treatment, whether you're taking insulin or oral medication. That's because it helps you determine whether your blood sugar is within the normal range and whether you need to adjust your medication accordingly.


The American Diabetes Association defines the healthy range for blood sugar as below 100 mg/dL.

How Can I Deal With an Insulin Reaction?

An insulin reaction refers to the symptoms you get when you take too much insulin and are experiencing low blood sugar or hypoglycemia. These include dizziness, sweating, hunger, and irritability, and can sometimes progress into confusion and fainting.


Keep at least 15 grams of easily-absorbed carbohydrates with you at all times to be used when you feel any of these symptoms. These can include candy (5 Lifesavers), non-diet soda (1/2 a cup), or fruit juice (1/2 a cup).


In the case of loss of consciousness, keeping a glucagon kit on your person and instructing family members or co-workers on how to use it can be life-saving. The kit comes with a powder dissolved in a liquid and injected using a syringe.


For all patients with type 1 and some with type 2 diabetes and gestational diabetes, insulin therapy is a critical part of their daily routine. It allows their bodies to metabolize carbohydrates without unusual blood sugar spikes that could lead to dangerous outcomes.


Insulin comes in different types and can be introduced to the bloodstream via different delivery methods. Depending on several factors, your doctor could prescribe you one or more types of insulin to manage your condition.


Of all the insulin basics to remember, ensure you're taking enough insulin and eating at the right time after taking it.

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