What is type 2 diabetes? Understanding the role of insulin and diabetes symptoms

The number of people living with diabetes in the UK has reached 4.7 million and of this number, one in 10 people over the age of 40 are living with a type 2 diabetes diagnosis. So, what is type 2 diabetes? Here are the top causes and signs to know.
Napala Pratini
min read
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Quick summary

  • Type 2 diabetes is when the body doesn't produce enough insulin, or respond correctly to insulin
  • Type 2 diabetes is caused by excess fat deposits inside of the liver and pancreas
  • The symptoms of type 2 diabetes can often be difficult to tell apart from other conditions, so it's important to see your doctor if you think something might be wrong

In 2015, The International Diabetes Federation reported that more than 400 million people were living with a disease called diabetes around the world.[1] In the UK, we spend £10B every year treating diabetes and its complications—which equates to about £20,000 every minute.[2] But what causes type 2 diabetes and what are its symptoms? This article will dive into these questions as well as explore insulin, the magic hormone that goes awry in diabetes.

What is type 2 diabetes?

Diabetes is a condition where blood glucose (or blood sugar—two different names for the same thing) levels are too high over a sustained period of time. It’s perfectly normal to have elevated blood glucose levels after eating, but with diabetes, they don’t come back down to normal levels at the rate that they should. There are two main causes of diabetes: Either your body doesn’t produce enough insulin, which is what we call type 2 diabetes, or your body can’t produce any insulin at all, which is called type 1 diabetes. Ninety percent of people with diabetes have type 2, which will be the focus of this article.[2]

More than 400 million people are living with diabetes globally

International Diabetes Federation

But let’s first take a step back… what is insulin and how does it link with blood sugar levels?

It all begins with one of the more curious, and not often talked about, organs in the body: the pancreas. It sits behind your stomach, is about 6 inches long, and looks a bit like a feather made of jelly (what a visual, eh?). The pancreas does many amazing jobs (including being the main organ for producing the enzymes that digest all our food), but one of its key responsibilities is to control the levels of sugar in our bodies.

The pancreas coordinates a beautiful feedback loop in the body that keeps blood sugar tightly controlled. 

After we eat a meal, the various macronutrients in our food (like fats, proteins, and carbohydrates) get broken down into glucose and absorbed into our bloodstream. When blood glucose levels go up, the pancreas releases a hormone called insulin, which tells your body to store that sugar as fat in lots of places (e.g. around your organs, in your muscles, or—more obvious to the naked eye—under your skin). By storing this sugar in different places, our blood glucose levels are lowered down and, voila, back to a normal, healthy range.

If, however, we skip a meal and our blood glucose level goes down, the pancreas releases a hormone called glucagon. This hormone is basically the opposite of insulin—it tells our body to break down stored sugar and therefore bring blood glucose up to normal levels.

While you go about your day, whatever you’re doing, the pancreas is always working to keep your blood glucose finely balanced so that you have enough energy to power your muscles, brain, and other organs, but not too much. As we’ll soon find out, elevated blood sugar levels can lead to a separate set of negative impacts.

When someone develops type 2 diabetes, their pancreas loses the ability to secrete insulin, and therefore, to keep blood sugar levels balanced.

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What causes type 2 diabetes?

To tell you the truth, there is no simple answer to this question as dozens of factors can play a role in the development of type 2 diabetes. But there is one thing—the storage of fat around important organs like the pancreas—that we know leads to an increased propensity for type 2 diabetes.

It all starts with energy (or calorie) excess. When the body consumes excess calories, it needs to do something with that extra energy, so we tend to store it rather than get rid of it like we do some other nutrients.

The body is really excellent at storing energy. Initially, we store glucose in the liver and muscles. But once those storage deposits are full, we need to store it somewhere else... and that’s when the insulin we secrete turns that excess sugar into fat.

The “fat” we usually think about is stored under our skin. However, invisible to the naked eye is fat stored around and inside our organs. This is the problematic fat that is seen in type 2 diabetes.

Fat deposits around the pancreas are toxic to the cells which produce insulin. The feedback cycle carried out by the pancreas through insulin secretion stops, pushing our blood glucose up further and further, and eventually causing all of the complications created by type 2 diabetes.

It was thought for many years that, once these cells stopped producing insulin, they’d never again be able to. But we have great news! Recent research has shown that type 2 diabetes is actually reversible in many cases!

Signs of type 2 diabetes

When your pancreas stops being able to produce the insulin needed to keep blood glucose levels at bay, the body takes charge and attempts to dispose of the excess glucose in the form of urine. In some people, this can lead to the following symptoms of type 2 diabetes, though it’s worth noting that 6 out of 10 people have no symptoms when they are first diagnosed with the condition.

Signs and symptoms of type 2 diabetes

  • Going to the toilet a lot, especially at night
  • Excessive thirst
  • Fatigue
  • Genital itching or thrush
  • Cuts and wounds taking longer to heal
  • Tingling, numbness, or pain in the hands and feet
  • Blurry vision
  • Increased hunger
  • Frequent infections
  • Areas of darkened skin, usually in the armpits or neck

If you experience any of these symptoms or are worried about your blood sugar levels, contact your GP. They'll talk through your symptoms and concerns with you and can arrange a blood test to find out if you have elevated blood sugar levels.

Is type 2 diabetes serious?

Type 2 diabetes is often misunderstood but it's important to treat it seriously. It's a lifelong condition and without proper management, can cause a number of health complications. Learning to live with type 2 diabetes can be challenging but with the right information and support, you can absolutely continue with your everyday activities while keeping your blood sugar levels in check. Some people will need medication to help control blood sugar spikes while others are able to manage it through healthier eating, being more active, and losing weight.


[1] Diabetes facts & figures. International Diabetes Federation. Retrieved 29 April 2021. Accessible here.

[2] The cost of diabetes. Diabetes UK. Retrieved 29 April 2021. Accessible here.

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