Diabetes: Understanding It Once and For All

Have you just been told you have diabetes? Maybe a family member has been diagnosed with diabetes? Perhaps you just want to know a little more about this illness?

Learning about an illness can be overwhelming and, at times, extremely confusing. In this article, we attempted to put together all the information we think you need to know to understand diabetes clearly.

A Look at the Statistics

According to the International Diabetes Federation1, approximately 463 million adults (20-79 years of age) were living with diabetes by the end of 2019; and by 2045, it is estimated this figure will rise to 700 million. Moreover, 1 in 5 people over 65 have diabetes, and 1 in 2 people with diabetes are undiagnosed. In addition, the World Health Organization (WHO) pointed out that 1.6 million deaths are directly attributed to diabetes each year. 

What Exactly is Diabetes?

So, what exactly is diabetes, and why is it becoming one of the leading health problems worldwide? Is it somehow a given for us to develop diabetes as we age? And how can we prevent it?

To start with, we need to get to know its causes and types. 


When we talk about diabetes, there are two things that we cannot ignore: blood sugar and insulin. When we eat food, for example, a piece of bread, its nutrients will be absorbed by our digestive system and converted into the chemical energy our body requires to function. The important nutrient, carbohydrates, from the bread will be broken down into glucose, a very small sugar molecule easily absorbed into the blood. The circulation of glucose in the blood is what we usually refer to as “blood sugar”.

However, getting glucose into our blood circulation does not mean that our body cells can use these “fuels” because the cell membrane acts as a barrier and prevents glucose from entering the cell. This is when insulin comes into play. Insulin is a hormone which gives an order to cells to open a door for glucose to enter. Moreover, if the amount of glucose exceeds the current needs of the cells, insulin promotes the conversion of glucose into glycogen2, which is stored in the liver and muscles for later use.

Diabetes is a chronic condition and happens when there is something wrong with the insulin production in the pancreas3. With abnormal insulin production blood sugar levels would be abnormally high. Over time, high blood sugar levels can damage your heart, eyes, feet and kidneys, all of which are known as complications of diabetes.


You may be aware that there are two types of diabetes: Type I and Type II but there are also some rarer types of diabetes. 

Type I

Type I diabetes4 is caused by the malfunction of beta cells5 in the pancreas because the body’s immune system targets  the wrong “enemy” and attacks those beta cells. Destruction of the beta cells leads to extremely low or even absent production of insulin. As a result, blood sugar is no longer under control and will be very high. Around 10% of all patients with diabetes have Type I diabetes and they need daily administration of insulin, either by injection or via a pump.

There is a genetic component to the disease, but its manifestation still requires an environmental trigger. Type I diabetes is formerly known as juvenile or childhood-onset diabetes as it generally occurs in younger age. Although it still holds true that Type I diabetes is predominantly early onset, studies found that there are also patients with later onset (over 50). This also applies to Type II diabetes, which is commonly thought to be a disease in elderly people but in recent years, it is increasingly seen in young adults and even children.

Type II

Type II diabetes6 is a little more complex. Beta cells in the pancreas of patients with Type II diabetes produce a normal level of insulin, however this insulin is not recognized or accepted by the cells. Your body produces insulin which acts as a trigger for the cells to initiate glucose pathways, but because cells do not recognise this type of insulin, there is no open pathway for glucose to enter the cell. Alternatively, in rarer cases, the cells just crack the door open, where only a few glucoses can enter. This is described more formally as “insulin resistance”. 

Ideally, as insulin is not very effective on cells, the pancreas could release more insulin to overcome this resistance, thereby compensating for low insulin efficacy. This is exactly what the pancreas will do in some people who do not develop the disease or have late onset diabetes.

In fact, Type 2 is more common because at the start, the pancreas has the ability to produce more insulin; but as time goes by, the pancreas becomes more and more burdened. Eventually, beta cells in the pancreas will “burn out” and insulin can no longer be produced. This might explain why Type II diabetes is often seen in older patients. 

Although studies have shown that the direct cause of Type II diabetes is the inability of the pancreas to overproduce insulin for compensation, the true trigger of the disease is insulin resistance. Excessive body weight, unhealthy diet, physical inactivity are all risk factors for insulin resistance.

Other Types

Gestational diabetes

Gestational diabetes7 is diabetes which is developed during pregnancy and disappears after giving birth. Although it can happen at any stage of the pregnancy, it is more common in the second or third trimester.

The high blood sugar level is usually caused by insulin resistance as a result of other hormones influencing the efficacy of insulin during pregnancy. Extra care needs to be taken of the patient as well as the fetus. 

Women who meet one or more characteristics below are at high risk of developing gestational diabetes during pregnancy:

  • overweight (BMI>308)
  • have experienced gestational diabetes before
  • have given birth to a baby who weighed 4.5kg (10lb) or more at birth
  • one of parents or siblings has diabetes
Maturity onset diabetes of the young (MODY)9

This type of diabetes is due to a single gene mutation. Children whose parents have this mutation will have a 50% chance of inheriting it and the disease usually manifests before the age of 25. 

Neonatal diabetes10

This type of diabetes is also caused by a genetic mutation and is usually diagnosed in children younger than six month old. It can be easily mistaken for Type I diabetes but Type I diabetes  rarely manifests itself as early as the age of six months. More importantly, for neonatal diabetes, beta cells dysfunction in the pancreas is not due to autoimmune attack.

Other Types of Diabetes

In addition, there are other diabetes which are even rarer, such as:

In some cases, diabetes is a result of medications or other diseases. As our focus is chronic diabetes which can be prevented or delayed, we will not go into the details of these rare types of diabetes. Nevertheless, it is always very important to understand which diabetes we are looking at, so that we  can use the correct prevention strategy or treatment. 


Type I and Type II diabetes share many common symptoms, but usually those for Type II diabetes appear more slowly. 

Type I

  • Feeling of abnormal thirst
  • Frequent urination, especially at night

Sudden weight loss without trying

  • Tiredness
  • Blurred vision

Type II

  • Feeling of abnormal thirst
  • More frequent urination, especially at night
  • Slow healing wounds
  • Recurrent thrush
  • Tingling or numbness in hands and feet.


Type I

There is no cure for Type I diabetes, but hopefully in the future, some types of immunotherapy17 can be developed as a potential cure. The current treatment for Type I diabetes is daily insulin administration. 

Type II

Type II diabetes has no cure either, but it can be controlled. 

The two most common medications for this type of diabetes are Metformin18 and Sulfonylureas19. The former increases insulin sensitivity and efficacy so that body cells can use insulin more effectively. The latter stimulates the pancreas to produce more insulin. 

Unlike Type I diabetes, insulin usually will not be administered right after you are diagnosed, as there are medications to stimulate the production of insulin from your own cells and to reduce insulin resistance. While most patients do need insulin administration (because the blood sugar levels are going higher even under other medication treatment), it is a common misconception that being treated with insulin means that you have not managed your diabetes well or your condition is severe. 

Type II diabetes is a chronic disease; the disease progression rate and patients’ body reaction to different medications vary from person to person. Insulin is just one of the medications among many diabetes medications that help you control your blood sugar level in a normal range. 

Last but not least, a possible condition that might develop with diabetes (no matter Type I or Type II) is hypoglycemia20 (blood glucose level too low). Insulin administration has a quite strong and fast effect on blood sugar level. This means, if you take in too much insulin, delay your meals or carry out excessive exercise without reducing your insulin intake, then your blood sugar level might be suppressed and cause hypoglycemia.


Since we are yet to be certain what causes Type I diabetes, there is not much we could do to prevent it. However, for Type II diabetes, we clearly understand what factors can put one at risk. This is a good thing, because we know what we can avoid or do to prevent Type II diabetes.

Research revealed that most Type II diabetes cases can be prevented if we adhere to a healthy diet and a regular exercise regimen. The cornerstone of the prevention strategy is to avoid being overweight or obese.

Healthy eating habits include but are not limited to:

  • Choosing drinks without added sugar and unsweetened dairy products
  • Cutting down on red and processed meat 
  • Cutting down on snacks (especially sweet ones)
  • Cutting down on salt (as high salt in food will lead to high blood pressure)
  • Eating food with more fiber and low GI (Glycemic Index)21
  • Eating more fruit and vegetables approved by your doctor
  • Reducing alcohol intake

Even though there is no cure for Type II diabetes, we do have a “cure” for “prediabetes”'. The best way to treat the disease is to prevent it from happening in the first place, and this is what everyone can achieve as long as they are willing to take actions to adopt a healthy lifestyle.

In Summary

In conclusion, since we do not know the cause of Type I diabetes, we can not prevent it from happening. However, with a few simple lifestyle changes such as losing excess body weight and improving our health, anyone can prevent Type II diabetes.

As you can see by the facts that we have presented, diabetes is quite a complex disease. We all know that diabetes could be caused by genetic predisposition, but also can be a result of interaction between your genes and your lifestyle.

Just as a last word, although Type II diabetes is a lifetime disease, it can be completely controllable. As long as you know how to control your blood sugar levels and live a healthy lifestyle, nobody can stop you from living a full life.


  1. International Diabetes Federation - Home [Internet]. Available from: https://idf.org/
  2. Glycogen is a stored form of glucose. It is a large multi-branched polymer of glucose which is accumulated in response to insulin and broken down into glucose in response to glucagon. [Internet]. Diabetes. 2019. Available from: https://www.diabetes.co.uk/body/glycogen.html
  3. The Digestive Process: What Is the Role of Your Pancreas in Digestion? [Internet]. 2019. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/the-digestive-process-what-is-the-role-of-your-pancreas-in-digestion
  4. Type 1 diabetes [Internet]. nhs.uk. 2022. Available from: https://www.nhs.uk/conditions/type-1-diabetes
  5. Beta cells are unique cells in the pancreas that produce, store and release the hormone insulin. [Internet]. Diabetes. 2019. Available from: https://www.diabetes.co.uk/body/beta-cells.html
  6. Type 2 diabetes [Internet]. nhs.uk. 2017. Available from: https://www.nhs.uk/conditions/type-2-diabetes/
  7. Gestational diabetes [Internet]. nhs.uk. 2017. Available from: https://www.nhs.uk/conditions/gestational-diabetes/
  8. What is the body mass index (BMI)? [Internet]. nhs.uk. 2018. Available from: https://www.nhs.uk/common-health-questions/lifestyle/what-is-the-body-mass-index-bmi/
  9. Maturity onset diabetes of the young (MODY) [Internet]. Diabetes UK. Available from: https://www.diabetes.org.uk/diabetes-the-basics/other-types-of-diabetes/mody
  10. Neonatal diabetes is a rare form of diabetes that is usually diagnosed in children under 6 months of age. [Internet]. Diabetes. 2019. Available from: https://www.diabetes.co.uk/neonatal-diabetes.html
  11. Wolfram syndrome [Internet]. Diabetes UK. Available from: https://www.diabetes.org.uk/diabetes-the-basics/other-types-of-diabetes/wolfram-syndrome
  12. Alstrom Syndrome – Support & Information [Internet]. Available from: https://www.alstrom.org.uk/
  13. Diabetes occurs in many types beyond type 1 diabetes and type 2 diabetes. One of these is Latent Autoimmune Diabetes of Adulthood (LADA). Some patients receive the diagnosis of type 2 diabetic, despite not exhibiting all the classic symptoms associated with this condition. In some instances, a more accurate diagnosis would be LADA. [Internet]. Diabetes. 2019. Available from: https://www.diabetes.co.uk/diabetes_lada.html 
  14. What is Type 3c diabetes? [Internet]. Diabetes UK. Available from: https://www.diabetes.org.uk/diabetes-the-basics/type-3c-diabetes
  15. Steroid-induced diabetes [Internet]. Diabetes UK. Available from: https://www.diabetes.org.uk/diabetes-the-basics/other-types-of-diabetes/steroid-induced-diabetes
  16. Cystic fibrosis diabetes [Internet]. Diabetes UK. Available from: https://www.diabetes.org.uk/diabetes-the-basics/other-types-of-diabetes/cystic-fibrosis-diabetes
  17. What is immunotherapy| Cancer Research UK [Internet]. Available from: https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/immunotherapy/what-is-immunotherapy
  18. Metformin: a medicine to treat type 2 diabetes [Internet]. nhs.uk. 2022. Available from: https://www.nhs.uk/medicines/metformin/ 
  19. Sulphonylureas are a class of oral medications that control blood sugar levels in patients with type 2 diabetes by stimulating production of insulin. [Internet]. Diabetes. 2019. Available from: https://www.diabetes.co.uk/diabetes-medication/sulphonylureas.html 
  20. Low blood sugar (hypoglycaemia) [Internet]. nhs.uk. 2017. Available from: https://www.nhs.uk/conditions/low-blood-sugar-hypoglycaemia/ 
  21. What is the glycaemic index (GI)? [Internet]. nhs.uk. 2018. Available from: https://www.nhs.uk/common-health-questions/food-and-diet/what-is-the-glycaemic-index-gi/ 

Adina Zhao

Medical Bioscientist - Imperial College London Medical Bioscience BSc
Modules covered: Integrative Body Systems, Molecular and Cellular Biology, Chemistry of Biological Interactions.
Past projects: Investigation of the influence of amino acid mutations of in-cluster gene lmbU on LmbU protein transcription and translation efficiency in Streptomyces lincolnensis, Investigation of the influence of red fluorescence protein mCherry on the photosynthetic efficiency of Arabidopsis thaliana .

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