Type 2 diabetes has long been regarded as a life-long condition that steadily gets worse, always needing more and more tablets and eventual insulin injections. It is widely regarded as being caused by obesity.
Gestational diabetes, on the other hand, is believed to just disappear after pregnancy.
Now we know that all these ideas are wrong. Let’s look at them one at a time.
Life-long and inevitably progressive?
Since the late 1970s, I have been listening to my patients with type 2 diabetes and trying to understand exactly what was going wrong.
We studied each kind of tissue in turn – fat, muscle and liver. But then we had the opportunity to be able to look at what was happening in all three of them at the same time by using a powerful MRI scanner. Our early studies showed that too much fat in the wrong place caused problems with controlling glucose. We also learned that, after bariatric surgery, sugar levels returned to normal within days. Bingo!
As such, I was able to explain type 2 diabetes – in theory. That was 2006, and since then we have been steadily testing each bit of what I like to call the ‘Twin Cycle Hypothesis’. We have since proven that those cycles can be made to spin in the reverse direction – by losing about two-and-a-half stone in weight.
To do the studies, we needed a way of helping people lose that amount of weight. But, by that time, I knew why people found weight loss very difficult – the diet had to be an unexacting daily decision, cause little in the way of hunger and be followed for a short period of time only. Those early studies gave dramatic results.
In a recent study, I teamed up with Professor Mike Lean of Glasgow University to test this approach used by practice nurses (or dietitians) in Primary Care. Over two years, one in three people lost enough weight and kept it off. This meant that over one third of patients had become non-diabetic, no longer having to take any diabetes tablets at all.
Caused by ‘obesity’?
Obesity has a strict definition: a body mass index (BMI) of over 30. At the time type 2 diabetes is diagnosed, however, one in two people have a BMI of under 30. One in 10 have a BMI in the ‘normal’ range of less than 25.
Our studies show that if people who happen to have a very high BMI lose the same amount of weight (two-and-a-half stone) as those who aren’t considered ‘obese’, they can still become non-diabetic.
Ultimately, obesity does not cause type 2 diabetes. We have shown that it is, in fact, caused by around half a gram of excess fat inside the cells of the pancreas. Stored under the skin, fat is safe even though it may not be a welcomed sight to its owner.
Some people have a very low threshold for letting fat be stored outside what we call the ‘safe depots’. They might get type 2 diabetes at a BMI of 23. Other people have a higher threshold for letting fat build up in the wrong place.
As such, we should be talking about Personal Fat Thresholds instead. A person with true type 2 diabetes is carrying more fat than they can cope with metabolically – whatever their BMI. Pre-disposition therefore plays a large role in determining whether or not you might get the condition.
But beware of two things. Firstly, not all diabetes is type 2. Sometimes, type 1 diabetes (nothing to do with fat) can come on slowly in adult life and at first be confused with type 2. There are also rarer forms of diabetes. Secondly, a demographic time bomb is ticking: so many children are carrying more fat than is good for them and get to their early 20s already too heavy. They may get type 2 diabetes even without increasing weight in adult life.
Gestational diabetes forgotten after pregnancy?
Women who have raised blood sugar levels in pregnancy have an increased chance of getting type 2 diabetes in the future. The higher risks of heart trouble can kick in even before the slowly developing type 2 diabetes is recognised. Even more pressing is the fact that there is a much higher chance of diabetes in a subsequent pregnancy.
Our research has shown that in pregnancy when gestational diabetes has been picked up, very modest calorie restriction can avoid the need for tablets or insulin. Research now underway is gathering more detail about this approach.
We know for certain that losing weight before pregnancy results in a much lower chance of a baby being exposed to high sugars. There is very clear information about how the risk of all kinds of trouble in pregnancy and delivery rises with higher body weights and this applies especially to women who have had gestational diabetes.
The importance of getting down to your fittest weight in preparing for a pregnancy has not yet been empathized enough.
Professor Roy Taylor will be returning to this guest post to answer some user questions on Tuesday 18 February at 3pm.
The author is donating 100% of his proceeds from this book to Diabetes UK.
Life Without Diabetes is available on Amazon (RRP £9.99)