Type 1 vs Type 2 Diabetes: The Key Differences (UK)

Type 1 and type 2 diabetes share a name, a blood test and a lot of confusing headlines, but they are very different conditions. In type 1, the immune system destroys the cells in the pancreas that make insulin, so the body produces little or none and needs insulin treatment from diagnosis. In type 2, the body still makes insulin, but it doesn't work properly or there isn't enough of it, and the condition usually develops slowly over years.

That one difference, no insulin versus insulin that isn't working well, explains almost everything else: who gets each type, how fast symptoms appear, how it's treated, and why weight matters so much more in one than the other.

Type 1 vs type 2 diabetes: the key differences

Before the detail, here is the side-by-side view most people are looking for.

The figures on prevalence come from Diabetes UK's latest statistics, and the rest of the table is unpacked below.

What insulin does, and why it matters here

Insulin is a hormone made by beta cells in the pancreas. After you eat, glucose from your food enters the bloodstream, and insulin acts like a key that lets that glucose move into your cells to be used for energy or stored.

Diabetes, in any form, means glucose is building up in the blood instead of getting where it needs to go. Over months and years, persistently high blood glucose can damage blood vessels and nerves, which is why the NHS lists complications affecting the eyes, kidneys, feet and heart.

Where the two main types differ is in why the key has gone missing.

What is type 1 diabetes?

In type 1 diabetes, the immune system mistakenly attacks and destroys the insulin-producing cells in the pancreas. The NHS describes it as an autoimmune condition where your body cannot make insulin, and is clear that it can't be prevented.

That point is worth dwelling on, because people with type 1 hear the opposite surprisingly often. Type 1 is not caused by eating too much sugar, by being overweight, or by anything the person did or didn't do. Exactly what sets off the immune attack still isn't fully understood, and there is currently no way to prevent it.

Type 1 often starts in childhood or young adulthood, but it can appear at any age. In adults it can be mistaken for type 2 at first, simply because type 2 is so much more common in grown-ups.

Symptoms of type 1 diabetes

Because insulin production collapses, symptoms tend to arrive fast. The NHS lists the main symptoms of type 1 as:

• Peeing more than usual, especially at night
• Being very thirsty
• Feeling very tired
• Losing weight without trying

Other signs include blurred vision, sweet or fruity-smelling breath, cuts that heal slowly, and repeated infections such as thrush. These usually develop over a few days or weeks.

Without insulin, the body starts breaking down fat for fuel at a rate that produces acids called ketones. If ketones build up, it can lead to diabetic ketoacidosis (DKA), which is life-threatening. The NHS advises calling 999 or going to A&E if diabetes symptoms come with stomach pain, vomiting or diarrhoea, sleepiness or confusion, or fast, deep breathing.

How type 1 is treated

Everyone with type 1 diabetes needs insulin, because the body can no longer make its own. The NHS explains that insulin is the main treatment, taken either as several injections a day with an insulin pen or through a pump worn on the body.

Technology has changed day-to-day life with type 1 considerably. Continuous glucose monitors track levels around the clock, and some pumps now link to a monitor and adjust insulin automatically. These hybrid closed loop systems are being rolled out gradually on the NHS.

The trade-off with insulin is the risk of hypoglycaemia, or a "hypo", when blood glucose drops too low. Managing type 1 well means balancing insulin against food, activity, illness and stress every single day, which is a lot more work than most people realise.

What is type 2 diabetes?

In type 2 diabetes, the pancreas still makes insulin, but either it doesn't make enough or the body's cells stop responding to it properly. The NHS describes it as when insulin does not work properly or there is not enough of it. The cells becoming less responsive is called insulin resistance.

For a while, the pancreas compensates by producing more insulin. Over time it struggles to keep up, and blood glucose creeps upwards. This is why type 2 tends to arrive gradually, often passing through a stage called prediabetes first.

Diabetes UK estimates that almost 6 million people in the UK are living with diabetes, including almost 1.3 million who may have type 2 without knowing it, and a further 6.9 million who are at increased risk because of their blood glucose levels.

Who is at risk of type 2 diabetes?

Unlike type 1, type 2 has well-understood risk factors. According to Diabetes UK, your risk is higher if you:

• Are over 40, or over 25 if you're of African-Caribbean, Black African, Chinese or South Asian background
• Have a parent, brother, sister or child with type 2 diabetes, which makes you 2 to 6 times more likely to develop it
• Are of South Asian, African-Caribbean or Black African descent, where type 2 is two to four times more likely
• Are living with overweight or obesity, or have a high waist measurement
• Have ever had high blood pressure
• Have had gestational diabetes, polycystic ovary syndrome (PCOS), a heart attack or a stroke

Diabetes UK also lists smoking, heavy drinking, long periods of sitting, and too little or too much sleep. We've looked at the sleep side of this in more detail in our guide asking whether 7 hours of sleep is enough.

Weight sits at the centre of that list for a reason. Excess fat, particularly around the abdomen and in the liver, makes insulin resistance more likely. Diabetes UK describes current diagnosis numbers as an all-time high, and they have risen alongside UK obesity levels, which we've charted in our UK obesity statistics.

Symptoms of type 2 diabetes

The NHS lists the most common symptoms of type 2 as feeling very tired, peeing more than usual, feeling thirsty all the time and losing weight without trying, plus blurred vision and slow-healing cuts.

On paper that looks almost identical to type 1. The difference is pace. Type 2 symptoms, if they appear at all, tend to build so slowly that people put them down to getting older, being busy or not sleeping well. The NHS is blunt that not everyone with type 2 has symptoms, which is why so many people are diagnosed by chance during a routine blood test or an NHS Health Check.

How each type is diagnosed

Both types are usually picked up with blood tests that measure glucose. HbA1c is the most common: it reflects your average blood glucose over the previous two to three months.

According to Diabetes UK, an HbA1c of 42 to 47 mmol/mol indicates prediabetes, and 48 mmol/mol or above is in the range for type 2 diabetes. If you've had a result back and aren't sure what it means, our guide to the HbA1c normal range in the UK walks through each band.

When type 1 is suspected, things move faster. The NHS says a GP will do a finger-prick test and, if type 1 is possible, refer you to a hospital specialist, usually the same day. The specialist confirms the type based on things like age, weight and symptoms, and may use extra blood tests when it isn't clear.

How type 2 is treated

Treatment for type 2 usually starts with diet, activity and, where relevant, weight. The NHS notes that lifestyle changes can lower blood glucose, and suggests eating more vegetables, fruit and wholegrains, aiming for about 2.5 hours of activity a week, stopping smoking and cutting down on alcohol.

If medicine is needed, the NHS says:

• Metformin, which improves how the body handles insulin, is usually offered together with an SGLT2 inhibitor, which helps the body pass extra glucose out in urine, if you have no other serious conditions
• GLP-1 receptor agonists, given as weekly injections, may be offered if you have a history of heart disease, or if you have obesity and other treatments haven't worked
• Insulin may be used when other medicines aren't controlling blood glucose well enough

Which medicines are right depends on your other health conditions, your kidney function, your weight and how your blood glucose responds, so these decisions sit with your GP or diabetes team. National guidance on managing type 2 in adults is set out in NICE guideline NG28. If you're curious about how the GLP-1 class works in the body, we've explained it in plain English in how GLP-1s work.

Everyone diagnosed with type 2 in England should also be offered a free diabetes education course within a year of diagnosis. They're worth taking up. Knowing what your numbers mean makes every appointment more useful.

Can type 2 diabetes go into remission?

Sometimes, yes. Remission means your blood glucose has returned to a healthy range without needing diabetes medicine. The NHS says it may be possible to prevent type 2 diabetes or put it into remission by losing weight and improving your diet.

The strongest evidence comes from DiRECT, a UK trial run across 49 GP practices in Scotland and Tyneside. People with type 2 who followed a structured, clinically supervised weight management programme were far more likely to be in remission after a year than those receiving usual care: 46% compared with 4%. Remission only happened in people who lost weight.

A few honest caveats. Remission isn't achievable for everyone, and it isn't the same as a cure: blood glucose can rise again if weight comes back, so regular check-ups still matter. The programme in DiRECT used a very structured diet under close supervision, and the NHS advises that very strict low-calorie diets should be discussed with a health professional before you start. Sustainable changes you can keep up are what protect you long term.

Type 1 can't be put into remission through weight loss or diet, because the problem is the loss of insulin-making cells rather than how well insulin works.

Where weight fits in for each type

This is where the two conditions diverge most sharply, and where a lot of stigma creeps in.

In type 2, weight is a major modifiable risk factor. Losing weight, if you're carrying extra, improves insulin sensitivity, lowers blood glucose, and can reduce the need for medication or even lead to remission. Building meals around protein, vegetables and fibre helps with fullness and steadier blood glucose; our list of high-protein, low-calorie foods is a practical place to start.

In type 1, weight didn't cause the condition, and losing weight won't reverse it. That said, people with type 1 can also gain weight and develop insulin resistance, which can mean needing more insulin. Any weight loss plan with type 1 should be agreed with the diabetes team, because changes in food intake and activity directly affect insulin doses and the risk of hypos.

And for both types: blame doesn't help anyone. Type 2 risk is shaped by family history, age, ethnicity, sleep and blood pressure as well as weight, and plenty of people with every risk factor never develop it. What helps is knowing your risk, getting tested, and having support to make changes that last.

Other types of diabetes worth knowing about

Type 1 and type 2 account for around 98% of diagnoses, but Diabetes UK describes several rarer types, including:

• LADA (latent autoimmune diabetes in adults), sometimes called "type 1.5", which has features of both type 1 and type 2
• MODY (maturity onset diabetes of the young), a rare form caused by a single gene change that runs strongly in families
• Type 3c, which happens when another condition, such as pancreatitis or cystic fibrosis, damages the pancreas
• Steroid-induced diabetes, which can follow treatment with steroid medicines

If your diagnosis doesn't seem to fit, for example you were told you have type 2 but you're slim, young and needing insulin quickly, it's reasonable to ask your doctor whether further tests could clarify the type.

When to get checked

Book a GP appointment if you have any of the symptoms above, or if you have several risk factors for type 2, even if you feel completely well. In England, eligible adults aged 40 to 74 are also invited for a free NHS Health Check through their GP practice.

Get urgent help through your GP or NHS 111 if you suspect type 1, and call 999 if symptoms come with vomiting, stomach pain, confusion or fast, deep breathing.

This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting any treatment.