Insulin Therapy For Type 2 Diabetes

  • Hai Long Le MPharm, University of Birmingham
  • Zayan Siddiqui BSc in Chemistry with Biomedicine, KCL, MSc in Drug Discovery and Pharma Management, UCL

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Type 2 diabetes mellitus (T2DM) is the most common form of diabetes, accounting for 90% of all diabetes cases.1 T2DM is caused by the body becoming resistant to one of your hormones; insulin, which is responsible for moving sugar in the blood into the cells.1 Over time this will cause a buildup of sugar in the blood which is called hyperglycemia, and your body will produce more insulin as a result.1 Over time your body will stop producing as much insulin and this results in T2DM.1 

There are a number of factors which can increase the risk of developing T2DM; age, typically those above 45, poor dieting, a lack of exercise, being overweight, and a family history of the disease all contribute towards the onset of the disease.1 Additionally, T2DM is becoming more and more common in children and young adults due to increasing levels of obesity.1

Insulin therapy, a treatment for T2DM, involves the routine injection of insulin to mimic the body’s natural metabolism.2 The frequency of injections is tailored to the individual's needs. Insulin therapy is generally considered the final treatment option for T2DM when the disease has progressed, and alternate interventions stop working.2 However, it has been found that insulin therapy can be used briefly in newly diagnosed patients to help restore insulin production.2 This article will explain the basis of type 2 diabetes mellitus, as well as why, when, and how insulin therapy is used to treat this disease.

Understanding type 2 diabetes

Before we talk about diabetes itself, it is important to discuss the role insulin plays in maintaining the body's normal functions and why it is so important. When we eat, our body digests the food and enzymes break it down and transform it primarily into glucose. This is a type of sugar that the body uses to make energy. After a big meal, there is a big surge in blood glucose levels and insulin is released, tasked with getting the glucose into cells where it can be stored or used.3 It is very important for blood glucose levels to remain at a consistent level, as high blood glucose levels result in hyperglycemia; a condition which can cause a plethora of health complications such as heart disease and Alzheimer’s dementia.4,5

People who develop type 2 diabetes mellitus will first have a decreased reaction to insulin; this is called insulin resistance. Insulin communicates with cells in the body by binding to insulin receptors on the outside of cells.6 These are similar to armed gates; when insulin comes along they open the “gates” and allow glucose in. Insulin resistance lowers insulin's effectiveness at this and, as such, the pancreas (where insulin is produced) will pump even more insulin into the blood to make up for it. Eventually, the pancreas will stop producing so much insulin which marks the onset of T2DM.6

Type 2 diabetes mellitus has a range of associated symptoms, including; extreme thirst, increased urination, fatigue, weight loss, and vision issues.7 Due to the progressive nature of the disease these can increase over time without treatment. If you notice these symptoms it is advised to seek a healthcare professional.

Why use insulin therapy

Insulin therapy is not generally the first port of call when treating type 2 diabetes mellitus. If the disease is caught early it can generally be managed through lifestyle changes. Doctors will recommend a varied but healthy diet, lowering the consumption of fats, sugars and salts. Doctors will also suggest regular exercise and help you maintain a healthy weight.8 As the disease progresses to the point that diet and exercise are no longer effectively keeping blood glucose levels down, oral medication may be advised.8 It is then, only after the failure of oral medication that insulin therapy is suggested.2

But what does insulin therapy do exactly? For this treatment, patients received insulin injections on a regular basis that mimic the body’s production of insulin after and between meals. There are many different types of insulin available, some fast-acting and some slow-acting, so this treatment can be honed and specified to the individual.2 This treatment does not cure T2DM and therefore requires a long-term commitment, which can be daunting for patients.

Insulin administration

The administration of insulin can be a scary prospect for patients, especially for those who are afraid of needles. It can, unfortunately, be a source of discomfort and anxiety and increase the burden of the disease, however, there are some options to make this administration process more comfortable.

  • Insulin syringes: the most common and affordable method of insulin administration. The site of the injection is usually the stomach (around the belly button), the thigh, or the buttocks.9 You shouldn’t use the same site of injection twice, leaving at least a centimetre between points, as lumps can appear.10 It is advised to speak to your healthcare practitioner regarding the needle length and gauge, as this might be able to be adjusted for your comfort.9
  • Insulin pens: these are good for discretely administering and travelling with insulin, many insulin pens have been kitted with smart technology to relieve some of the pressure on the patients.9 Smart insulin pens can include; an adjustable dial to finetune dose, dose tracking, and display the time since the last dose.11
  • Insulin pumps: these are pre-programmed and adjustable pumps that need to be changed every 2 to 3 days. These can be a good option for those who do not want to inject via a syringe or pen every day.9 Insulin pumps can be hard to come by and expensive, so if you are interested in this administration method it is worth talking to your healthcare team.

Monitoring and adjusting insulin therapy

Aside from a person's metabolism, there are many factors that contribute to blood glucose levels. Diet, both what a person eats and how frequently, can cause spikes in concentration shortly after eating. Exercise uses energy and depletes sugar levels, thus lowering blood glucose levels. Even certain medications can have an impact. These fluctuations all unique to the individual in question necessitate regular monitoring of blood glucose levels to ensure the correct amount of insulin is administered at the correct time, preventing hypo- and hyperglycemia. Most patients will be able to monitor this on their own, using a finger prick tool and get an instantaneous reading.12

Potential complications and considerations

When considering complications of type 2 diabetes mellitus and insulin therapy, it is easy to only think about issues with the body, however, it is extremely important to also think about mental health. T2DM can be a burdensome disease to live with, as the lifestyle changes involved can seem daunting and upheave your daily routine. Additionally, strict dieting often associated with T2DM can lead to disordered eating and body image, so it’s incredibly important to have a strong support group of friends, family, and healthcare professionals around you.

In regards to specifically insulin therapy, the prospect of daily injections can be scary, as a fear of needles is exceptionally common. Having to remember to bring insulin when travelling and administering insulin in public spaces can make the patient feel both stressed and embarrassed, however, dealing with a chronic condition should never bring about embarrassment.

It is also worth considering cost when deciding upon insulin therapy. Depending on where in the world you live insulin can be very expensive, and since insulin therapy is a lifelong treatment, the cost can rack up quickly. Furthermore, specific equipment, such as an insulin pump, can be a large upfront cost that might not be financially available to many people.

When it comes to the physical complications regarding insulin therapy, there is a risk of both hypoglycemia and hyperglycemia. Due to insulin therapy being tailored to the individual, it can take a while to settle on the correct dose and frequency of insulin injections. If too much insulin is given to a patient, too much glucose in the blood will be taken up by the cells causing hypoglycemia. Symptoms include; dizziness, hunger, sweating, and shaking.13 It is very important for such symptoms to be monitored so hypoglycemia can be treated swiftly. On the other hand, if not enough insulin is administered, hyperglycemia can occur, with all the associated symptoms of diabetes. 

An unexpected complication of insulin therapy is weight gain of typically 2 to 4 kilograms. This could be due to a plethora of reasons but it is theorised this is caused by either overeating as a result of hypoglycemia or the body not expending as much energy as blood glucose levels are now stable.2

It is always advised to have a thorough conversation with your healthcare professional about any concerns you might have about starting a new treatment.


Type 2 diabetes mellitus is a chronic disease that can worsen over time and necessitate the use of insulin therapy to control blood glucose levels and prevent hyperglycemia. If left untreated this disease can lead to heart problems and dementia, so it is important to seek help if symptoms of diabetes arise and actively stay on top of any treatments. In conjunction with lifestyle changes; exercise and dieting, a person with T2DM can maintain a healthy level and live a relatively symptom-free life with insulin therapy. 

Insulin therapy is a life-long therapy requiring daily doses of insulin, however, novel modified insulins can be incorporated into the treatment routine providing long-lasting effects and lowering the frequency of administration. Additionally, the advent of smart technology and insulin pumps can help patients manage doses of insulin better, relieving patients of some of the burden of the disease.

As with any treatment, there are risks. Hypoglycemia and weight gain being the most common side-effects of insulin therapy, can be managed by consistent monitoring of blood insulin levels. To conclude, insulin therapy is a safe and effective treatment for this chronic disease.


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  13. CDC. Centers for Disease Control and Prevention. 2021 [cited 2024 Jan 15]. Low blood sugar(Hypoglycemia). Available from:

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Elijah Cacicedo-Hough

BS (Biological and Medicinal Chemistry), University of Exeter, United Kingdom

Elijah is a first class graduate from the University of Exeter, with a BSc in Biological and Medicinal Chemistry, earning multiple awards during their studies, including the Deans Award. Having developed a novel ionophore precursor for the sequestration of calcium, Elijah has both laboratory and research experience. With a specific interest in pharmacology, microbiology and disease, Elijah is a passionate medical writer who wants to help make science more accessible to everyone. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
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