What is the true cause of type 2 diabetes?
Diabetes Type 2
Type 2 diabetes is a disease in which your blood glucose, or blood sugar, levels are too high. Glucose is your main source of energy. It comes from the foods you eat. A hormone called insulin helps the glucose get into your cells to give them energy. If you have diabetes, your body doesn’t make enough insulin or doesn’t use insulin well. The glucose then stays in your blood and not enough goes into your cells.
Over time, having too much glucose in your blood can cause health problems. But you can take steps to manage your diabetes and try to prevent these health problems.
What causes type 2 diabetes?
Type 2 diabetes may be caused by a combination of factors:
- Being overweight or having obesity
- Not being physically active
- Genetics and family history
Type 2 diabetes usually starts with insulin resistance. This is a condition in which your cells don’t respond normally to insulin. As a result, your body needs more insulin to help the glucose enter your cells. At first, your body makes more insulin to try to get cells to respond. But over time, your body can’t make enough insulin, and your blood glucose levels rise.
Who is at risk for type 2 diabetes?
You are at higher risk of developing type 2 diabetes if you:
- Are over age 45. Children, teenagers, and younger adults can get type 2 diabetes, but it is more common in middle-aged and older people.
- Have prediabetes, which means that your blood sugar is higher than normal but not high enough to be called diabetes
- Had diabetes in pregnancy or gave birth to a baby weighing 9 pounds or more.
- Have a family history of diabetes
- Are overweight or have obesity
- Are Black or African American, Hispanic/Latino, American Indian, Asian American, or Pacific Islander
- Are not physically active
- Have other conditions such as high blood pressure, heart disease, stroke, polycystic ovary syndrome (PCOS), or depression
- Have low HDL (good) cholesterol and high triglycerides
- Have acanthosis nigricans — dark, thick, and velvety skin around your neck or armpits
What are the symptoms of type 2 diabetes?
Many people with type 2 diabetes have no symptoms at all. If you do have them, the symptoms develop slowly over several years. They might be so mild that you do not notice them. The symptoms can include:
- Increased thirst and urination
- Increased hunger
- Feeling tired
- Blurred vision
- Numbness or tingling in the feet or hands
- Sores that do not heal
- Unexplained weight loss
How is type 2 diabetes diagnosed?
Your health care provider will use blood tests to diagnose type 2 diabetes. The blood tests include:
- A1C test, which measures your average blood sugar level over the past 3 months
- Fasting plasma glucose (FPG) test, which measures your current blood sugar level. You need to fast (not eat or drink anything except water) for at least 8 hours before the test.
- Random plasma glucose (RPG) test, which measures your current blood sugar level. This test is used when you have diabetes symptoms and the provider does not want to wait for you to fast before having the test.
What are the treatments for type 2 diabetes?
Treatment for type 2 diabetes involves managing your blood sugar levels. Many people are able to do this by living a healthy lifestyle. Some people may also need to take medicine.:
- A healthy lifestyle includes following a healthy eating plan and getting regular physical activity. You need to learn how to balance what you eat and drink with physical activity and diabetes medicine, if you take any.
- Medicines for diabetes include oral medicines, insulin, and other injectable medicines. Over time, some people will need to take more than one type of medicine to control their diabetes.
- You will need to check your blood sugar regularly. Your health care provider will tell you how often you need to do it.
- It’s also important to keep your blood pressure and cholesterol levels close to the targets your provider sets for you. Make sure to get your screening tests regularly.
Can type 2 diabetes be prevented?
You can take steps to help prevent or delay type 2 diabetes by losing weight if you are overweight, eating fewer calories, and being more physically active. If you have a condition which raises your risk for type 2 diabetes, managing that condition may lower your risk of getting type 2 diabetes.
NIH: National Institute of Diabetes and Digestive and Kidney Diseases
- Type 2 Diabetes (American Diabetes Association)
- Type 2 Diabetes (Mayo Foundation for Medical Education and Research)
- What is Diabetes? (National Institute of Diabetes and Digestive and Kidney Diseases) Also in Spanish
- Diabetes Type 2 Symptoms (American Diabetes Association)
Diagnosis and Tests
- A1C: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
- Diabetes Tests (National Library of Medicine) Also in Spanish
- Diabetes Tests & Diagnosis (National Institute of Diabetes and Digestive and Kidney Diseases) Also in Spanish
- Insulin in Blood (National Library of Medicine) Also in Spanish
- Ketones in Blood (National Library of Medicine) Also in Spanish
- Ketones in Urine (National Library of Medicine) Also in Spanish
Prevention and Risk Factors
- How to Prevent Diabetes: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
- National Diabetes Prevention Program: Find a Program (Centers for Disease Control and Prevention)
Treatments and Therapies
- Diabetes and Dietary Supplements (National Center for Complementary and Integrative Health) Also in Spanish
- Diabetes Medicines: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
- Women and Diabetes — Diabetes Medicines (Food and Drug Administration)
- 4 Steps to Manage Your Diabetes for Life (National Institute of Diabetes and Digestive and Kidney Diseases) Also in Spanish
- Changing Your Habits for Better Health (National Institute of Diabetes and Digestive and Kidney Diseases) Also in Spanish
- Diabetic Diet: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
- Get to Know Your Diabetes Care Team (American Diabetes Association)
- Monitoring (Association of Diabetes Care and Education Specialists)
- Understanding Diabetes and Mental Health (American Diabetes Association)
- Weight Loss (American Diabetes Association)
- Where Do I Begin with Type 2? (American Diabetes Association)
- 6 Things to Know about Type 2 Diabetes and Dietary Supplements (National Center for Complementary and Integrative Health)
- Acanthosis Nigricans (Mayo Foundation for Medical Education and Research) Also in Spanish
- Diabetes Diet, Eating, and Physical Activity (National Institute of Diabetes and Digestive and Kidney Diseases) Also in Spanish
- National Diabetes Prevention Program (Centers for Disease Control and Prevention)
- Prediabetes:MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
- Speak Up — Diabetes: Five Ways to Be Active in Your Care at the Hospital (Joint Commission) — PDF
- Symptoms and Causes of Diabetes (National Institute of Diabetes and Digestive and Kidney Diseases) Also in Spanish
- Learn the Genetics of Diabetes (American Diabetes Association)
- Type 2 diabetes: MedlinePlus Genetics (National Library of Medicine)
Type 2 Diabetes
Type 2 diabetes is characterised by the body being unable to metabolise glucose (a simple sugar). This leads to high levels of blood glucose which over time may damage the organs of the body.
From this, it can be understood that for someone with diabetes something that is food for ordinary people can become a sort of metabolic poison.
Type 2 diabetes was formerly known as non-insulin-dependent or adult-onset diabetes due to its occurrence mainly in people over 40. However, type 2 diabetes is now becoming more common in young adults, teens and children and accounts for roughly 90% of all diabetes cases worldwide.
How serious is type 2 diabetes?
Type 2 diabetes is a serious medical condition that often requires the use of anti-diabetic medication, or insulin to keep blood sugar levels under control. However, the development of type 2 diabetes and its side effects (complications) can be prevented if detected and treated at an early stage.
Following pre-diabetes or metabolic disorder, type 2 diabetes can potentially be avoided through diet and exercise.
What causes type 2 diabetes?
Type 2 diabetes occurs when the hormone insulin is not used effectively by the cells in your body. Insulin is needed for cells to take in glucose (sugar) from the bloodstream and convert it into energy.
In advanced stages, type 2 diabetes may cause damage to insulin producing cells in the pancreas, leading to insufficient insulin production for your body’s needs.
Type 2 diabetes risk factors
A number of factors can increase the risk of developing type 2 diabetes.
- Being overweight or obese
- Having a waist size of 31.5 inches or more (women) or more than 37 inches (men)
- Eating an unhealthy diet
- Physical inactivity
- Having a first-degree relative with type 2 diabetes
- Having high blood pressure or raised cholesterol levels
- Being of South Asian and African-Caribbean descent
The likelihood of developing type 2 diabetes is also influenced by genetics and environmental factors. For example, research shows that:
- If either parent has type 2 diabetes, the risk of inheritance of type 2 diabetes is 15% 
- If both parents have type 2 diabetes, the risk of inheritance is 75% 
Is there an age where I’m more at risk of type 2?
Type 2 diabetes used to be known as adult-onset diabetes as it was primarily seen in middle-aged adults over the age of 40.
- See our guide on diabetes risk factors for more information.
Do you have to be overweight to get type 2 diabetes?
While being overweight is often associated with type 2 diabetes, someone who is a healthy weight can also be diagnosed with the condition
Often called ‘skinny’ type 2 diabetes, this condition can be found in individuals with low amounts of subcutaneous fat but high amounts of visceral or abdominal fat.
Symptoms and diagnosis
The most common symptoms of type 2 diabetes are:
- Excessive thirst
- Frequent urination
- Increased hunger
- Extreme tiredness
- Sudden loss of muscle mass
Some of these symptoms are the same for type 1 diabetes, but in type 2 diabetes they tend to develop more slowly over a period of months or years, making it harder sometimes for people to recognise them as signs of an underlying illness.
In fact, many people have type 2 diabetes for a long period of time before being diagnosed with the disease.
Type 2 diabetes is frequently diagnosed following the results of either a fasting plasma glucose test or an oral glucose tolerance test. The condition can also be detected through a general health check with your GP.
The condition can be detected through diabetes screening or may be picked up as part of other health checks.
Type 2 diabetes treatment
The NICE guidelines (NG28) state that treatment for type 2 diabetes should take into account an individual’s needs and preferences into account. People with diabetes should be given the opportunity to make informed decisions about their care and work together with healthcare professionals.
The NICE guidelines encourage having high-fibre, low-glycemic-index (low-GI) carbohydrate in the diet. This allows a good amount of flexibility and it is possible to follow a range of diets, including lower-carb and low-calorie, whilst ensuring you get a good source of low-GI foods such as vegetables, beans and pulses.
Your health team should help you with setting recommendations for carbohydrate and alcohol intake that work for you.
Adopting a lower-carb diet can help with weight loss and lowering of blood glucose levels. This is because metabolised carbohydrate turns into glucose in the bloodstream and has an impact on blood sugar.
- Speak to others following a low-carb diet in the Low Carb forum
- Join the Low Carb Program for people with type 2 diabetes, prediabetes and obesity
A low-calorie diet, which is supported by meal replacement soups or shakes has been shown to support help people with weight management and support type 2 diabetes remission.
Better known as the Newcastle diet, the DiRECT trial examined the benefits of a low-calorie diet on type 2 diabetes. Almost half of those who went on a low calorie diet achieved remission of their type 2 diabetes after one year.
A growing number of Diabetes Forum members have reversed their type 2 diabetes through both of the aforementioned methods.
Blood glucose testing
People with type 2 diabetes may also be prescribed tablets and/or injectable medication. Metformin is one of the most commonly prescribed drugs for people with type 2 diabetes and helps the body to better respond to insulin.
Other drug treatments are also available, including:
Type 2 diabetes and complications
Like type 1 diabetes, type 2 diabetes carries the risk of diabetes complications over time.
The most common complications of type 2 diabetes include:
- Heart disease
- Kidney disease (nephropathy)
- Eye disease (retinopathy)
- Nerve damage (neuropathy), which raises the risk of amputation
In fact, by the time they are diagnosed, 50% of people with type 2 diabetes show early signs of these health conditions.
The list of complications, which also includes depression and sexual dysfunction, is not pleasant but their risks can be reduced through good diabetes control and attending all diabetic screening appointments.
As with many chronic diseases, early diagnosis of type 2 diabetes is beneficial for treatment. Before type 2 diabetes develops, most patients exhibit pre-diabetic symptoms, and if treatment commences at this stage, diabetes of this type can be preventable.
- Almost 1 in 3 people with type 2 diabetes develops overt kidney disease 
- Within 20 years of diagnosis of type 2 diabetes, 60% of people diagnosed have some degree of retinopathy 
In terms of short term complications of diabetes, ketoacidosis is rare amongst type 2 diabetics. However, non-ketonic hyperglycemia is one threat type 2 diabetics should be aware of.
Impact of type 2 diabetes
As stated above, type 2 diabetes can lead to a greater chance of health problems which could in some cases affect your ability to work and could therefore affect your personal income.
Another factor to bear in mind is that increased care may be needed, from your family or from a carer, particularly as you get older.
With the right support and good diabetes management, the potential negative effects of type 2 diabetes can be minimised.
The NHS and type 2 diabetes
Type 2 diabetes is already one of the most common long term health conditions and the prevalence of type 2 diabetes in the UK is growing year on year.
The cost of treating a growing number of people with type 2 diabetes, and the health complications associated with the condition, is estimated to cost the NHS around £12 billion a year on direct and indirect care.
Famous people with type 2 diabetes
Famous people with type 2 diabetes include:
- Blues musician BB King
- Acclaimed director George Lucas
- British comedian Jimmy Tarbuck
- Music producer and American Idol judge Randy Jackson
- Grammy-award winning singer Patti LaBelle
- CNN anchor Larry King
- Tom Hanks
Type 2 diabetes statistics
According to the International Diabetes Federation (IDF), more than 537 million people across the globe have diabetes and this figure is predicted to rise to over 643 million by 2030
Of the total global diabetes population, 90% are living with type 2 diabetes but it is estimated that up to half of these people are unaware of their condition (undiagnosed diabetes).
In the UK, more than 4.7 million people are diagnosed with type 2 diabetes whilst a further 13.6 million people are believed to be at higher risk.
Reversing Type 2 Diabetes and ongoing remission
Hear all about from Professor Roy Taylor the 5 minute summary.
Our research has shown that:
• Type 2 diabetes is caused by a small amount of excess fat inside the liver and inside the pancreas
• It is a potentially reversible condition
• If a person has type 2 diabetes, they have become too heavy for their own body (nothing to do with the arbitrary concept of obesity)
• Weight loss of around 15kg is necessary for most people
• This can be achieved using a simple 3-step method: the 1, 2, 3 of diabetes reversal
• Type 2 diabetes is most easily reversed to normal in the early years after diagnosis
• How and why type 2 diabetes happens can now be understood
Read a full account in the book ‘Life Without Diabetes’ (published 2020 by ShortBooks)
A shorter how-to-do-it description– ‘Your Simple Guide to Reversing Type 2 Diabetes’ (published 2021 by ShortBooks)
Read Richard Doughty’s personal story Type 2 diabetes and the diet that cured me on the Guardian website, including a video interview of another personal story. You can also read an update from Richard, I reversed my diabetes in just 11 days, on the Mail Online.
Information for your doctor
Download our Information for Doctors (PDF: 227KB). Even though doctors do not like downloaded information from the web, this comes from an internationally recognised diabetes research centre. It is now being put into practice by both NHS England and NHS Scotland. The American Diabetes Association recognises remission of diabetes as an appropriate aim of management.
NHS England takes the research forwards
As a result of the new understanding of type 2 diabetes, NHS England is conducting a pilot scheme to determine the most cost effective way of delivering remission of type 2 diabetes: https://www.england.nhs.uk/diabetes/treatment-care/low-calorie-diets/
Publications relating to reversing diabetes can be found on this page.
The shakes can be found here
Preparing your own 800 calories per day diet is possible but challenging and time consuming. More information on this is given in the book ‘Life Without Diabetes’. Ready prepared fresh food providing a balanced diet of 800 calories per day can be ordered:
One other company offers ready prepared fresh food in the UK: The real Food Diet
- Life Without Diabetes
Life Without Diabetes
- Scientific Information
The information on this page is for doctors and scientists. It includes slides on various aspects of the reversal of Type 2 diabetes as well as published papers.
- Newcastle research has established that type 2 diabetes is caused by excess fat in liver and pancreas.
- If this fat is removed in the first ~6 years of diabetes, functional beta cell mass gradually returns to a completely normal level over 12 months in most people.
- The immediate loss of fat from the pancreas following weight loss is from a labile pool, and this is observed only in those with type 2 diabetes and not non-diabetic people.
- The small, irregular pancreas typical of type 2 diabetes returns towards normal volume, and returns to completely normal shape over 2 years of remission.
- Provided weight loss is maintained, beta cell function does not decline over the following years.
- The UK consensus definition of remission of type 2 diabetes [link to https://doi.org/10.15277/bjd.2019.221] is an HbA1c
Download our slides on:
- Counterpoint (PDF: 678KB)
- Counterbalance (PDF: 701KB)
- pancreas fat (PDF: 207KB)
- the DiRECT study (PDF: 95KB)
- personal fat thresholds (PDF: 481KB)
- Physiological mechanisms lecture to ADA (PDF: 375KB)
- Insulin secretion recovery during remission (PDF: 274KB)
- Pancreas volume during remission (PDF: 136KB)
In 2008, we published the Twin Cycle Hypothesis to explain the cause of Type 2 diabetes. This hypothesis predicted that diet could entirely reverse Type 2 diabetes. Read the scientific review, Pathogenesis of type 2 diabetes (PDF: 471KB) on the US National Library of Medicine website.
The Counterpoint study designed to test the hypothesis was funded by Diabetes UK. The results were very clear. Weight loss averaging 15kg (2 stone 5lb) achieved over 8 weeks caused two distinct sets of changes. Within seven days, liver fat had fallen by 30%, liver insulin sensitivity had returned to normal and fasting blood glucose had become normal. By eight weeks, pancreas fat content had returned to normal and insulin secretion by the pancreas had returned to normal. Read the full scientific paper, Reversal of Type 2 diabetes (PDF: 195KB) and the related Newcastle University Press Release, Diet Reverses Type 2 Diabetes.
This new understanding of what causes Type 2 diabetes and how it can be completely reversed has been used by individuals worldwide, a report has been published documenting practical management of Type 2 diabetes in respect of reversal (PDF: 85KB). A review describing the beta cell de-differentiation (PDF: 1081KB) explains why the condition is reversible. Under the endoplasmic reticulum stress caused by excess intracytoplasmic fat, the cell goes into a survival mode and switches off specialised gene expression. Removal of the fat permits re-differentiation. Scientists and doctors with access to the journal Diabetes Care, can read a full review of the science underlying this matter: Type 2 diabetes: etiology and reversibility (PDF: 363KB). See the more recent reviews: Diabetologia Review 2017 a discussion of practical aspects of achieving remission. The most recent reviews are in Lancet Diabetes & Endocrinology and in Journal of Internal Medicine
Professor Taylor was awarded the 2012 Banting Lectureship of Diabetes UK. Read his lecture Reversing the twin cycles of Type 2 diabetes (PDF: 543KB).
The pathophysiological basis of reversal of type 2 diabetes is described in 8 major papers:
- Lim EL, et al. Reversal of type 2 diabetes: Normalisation of beta cell function in association with decreased pancreas and liver triacylglycerol. Diabetologia 2011; 54: 2506-2514. PMID 21656330.
- Steven S, et al. Weight loss decreases excess pancreatic triacylglycerol specifically in type 2 diabetes. Diabetes Care 2016 Jan;39(1):158-65. doi: 10.2337/dc15-0750.
- Steven S, et al. Very low-calorie diet and 6 months of weight stability in type 2 diabetes: Pathophysiologic changes in responders and nonresponders. Diabetes Care 2016 May 39(5):808-15. doi: 10.2337/dc15-1942.
- Taylor R et al. Remission of human type 2 diabetes requires decrease in liver and pancreas fat content but is dependent upon capacity for beta cell recovery. Cell Metabolism 2018. Aug 2. pii: S1550-4131(18)30446-7. doi: 10.1016/j.cmet.2018.07.003. Taylor et al Cell Metabolism 2018.
- Rehackova L et al. Acceptability of a very-low energy diet in Type 2 Diabetes: patient experiences and behaviour regulation. Diabetic Medicine 2018. Nov;34(11):1554-1567. doi: 10.1111/dme.13426.
- Taylor et al. Understanding the mechanisms of reversal of type 2 diabetes. Lancet Diabetes Endocrinology 2019. May 13, pii: S2213-8587(19)30076-2. doi: 10.1016.
- Al-Mrabeh et al. Hepatic Lipoprotein Export and Remission of Human Type 2 Diabetes after Weight Loss. Cell Metabolism 2019. Dec 19, doi.org/10.1016/j.cmet.2019.11.018.
- Al-Mrabeh A, Hollingsworth KG. Shaw JAM, McConnachie A, Sattar N; Lean MEJ, Taylor R. 2-year remission of type 2 diabetes and pancreas morphology: a post-hoc analysis of the DiRECT open-label, cluster-randomised trial. Lancet Diabetes Endocrinol 2020; Dec 8; doi: 10.1016/S2213-8587(20)30303-X.
Professor Roy Taylor’s Full CV
Click Professor Roy Taylor’s CV
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