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Why GPs should prescribe a low-carb diet for type 2 diabetes



It seems every week brings a new headline about the catastrophic epidemic of type 2 diabetes that is threatening to overwhelm our health service. But in my view we are largely ignoring the root cause of the problem and taking completely the wrong approach to tackling it – failing our patients and costing the NHS a fortune in the process.

Instead of giving patients unhelpful instructions to eat less – on a diet based on starchy carbohydrate – and exercise more, and then putting them on to more and more drugs, we should be listening to their experience and observing the growing body of evidence that cutting down on carbohydrate intake is the key.

I am seeing astonishing results in patients with type 2 diabetes who themselves chose to reduce their dietary carbohydrate intakes. Having seen the results, and after many hours of research to understand the physiology better, I believe it would be unacceptable for me not to offer advice on using a ‘low-carb’ diet to patients with type 2 diabetes.

At medical school 20 years ago I was taught that type 2 diabetes is a progressive disease. This is not true – turn off the ‘sugar tap’ and the disease begins to reverse. Type 2 diabetes is a problem of homeostasis. Our body uses its various hormones, including insulin, to maintain blood glucose homeostasis of 4–6 mmol/L, which is about 5g in an average adult. But when we constantly consume food that challenges our blood glucose level, the body takes the hit and shifts the excess glucose to fat storage. Eventually, probably as a homeostatic mechanism to prevent ever-increasing obesity, our body starts to push back – and blood glucose rises.

So what do I now tell patients? I explain how type 2 diabetes is a problem of high blood glucose, insulin resistance and hyperinsulinaemia, and advise them that one option to manage this is to avoid sugar, processed foods, and sweet fruits, and eat less carbohydrate. Instead they can eat ‘real food’ which includes lots of above-ground vegetables, a typical portion of protein (meat, fish, eggs, nuts etc) each day and as much healthy fat such as olive oil to satisfy their appetite.

In a typical patient you see impressive results within a couple of months, including a significant drop in HbA1c (80 mmol/mol down to 50 mmol/mol would not be unexpected, sometimes even more). Triglycerides plummet and high-density lipopoprotein (‘good’) cholesterol increases. People notice effortless weight loss, including losing their mid-riff (the ‘insulin tyre’) – one patient advised I owe them £750 as they had to buy new clothes!

Many patients suffering from dyspepsia are able to stop their PPIs. Importantly, these results seem to be maintained, despite the argument that ‘there is no long-term randomised controlled trial evidence for the benefit of low carb diets’. There is no long-term trial evidence because there are no such trials; the longest that look at low carb diets seem to be 24 months. Let’s not mislead people when we say there is no long-term evidence.

Some GPs worry they are going against guidelines by advising a reduction in carbohydrate intake. They need not be concerned. NICE guidelines on type 2 diabetes advise high-fibre low glycaemic index (GI) sources of carbohydrate, which in practical terms means things such as peppers and leafy greens. It does not mean potatoes and bread, which are high GI.

NICE also advises tailoring the carbohydrate to the individual. In my experience most people need to eat less than 130g of carbohydrate a day (a few small potatoes and the odd slice of bread) although those with severe insulin resistance may need to reduce carbohydrate to 50g or less – which generally means completely removing starchy carbohydrate from the diet.

Other concerns some people have include: ‘Carbohydrates are essential in our diet.’ This is not true, there is no such thing as an essential carbohydrate, and our livers are pretty nifty at gluconeogenesis if required. 

‘Ketosis is dangerous.’ Actually, nutritional ketosis and ketoacidosis are completely different physiological processes – Google it, and also consider what happens when people fast: they do not become ketoacidotic. Nutritional ketosis is not dangerous (it actually makes you feel pretty good!)

I would recommend looking into low carbohydrate diets for managing type 2 diabetes. It may be the most interesting CPD you have done for a while, it will revolutionise your consultations, and it may have a significant impact on your own health.

As one my patients, a very happy male in his mid-60s, testifies:

‘I was initially quite angry when told I could reverse my type 2 diabetes. I was angry because for 12 years the NHS (doctors, consultants and internet) told me the disease was irreversible and progressive. And of course they are right, if you follow the standard low fat high carbohydrate dietary advice.

‘I changed to a real food, low carbohydrate, healthy fat diet in August last year and the results are, at least to me, a miracle. I no longer take diabetes pills, or pills for gout, or for high cholesterol, and I take fewer blood pressure pills. I have far more energy and now enjoy life to the full.’

Dr Campbell Murdoch is a GP in Somerset, RCGP clinical advisor and Public Health England physical activity clinical champion

Further reading and resources

I recommend the books The Obesity Code by Dr Jason Fung, as well as his book Complete Guide to Intermittent Fasting. I also recommend The Real Meal Revolution by Professor Tim Noakes for a further dive into this area which includes great recipes. Dr Aseem Malhotra’s very recent book The Pioppi Diet is also excellent.

The website www.dietdoctor.com is very informative, and a great resource for patients and doctors, as is www.diabetes.co.uk.

There is also a huge network of GPs and other healthcare professionals across the country, who are very willing to share their knowledge. I would be very happy for anyone to contact me at campbell.murdoch@nhs.net