Could you have silent diabetes? Here’s how to tell – and what you can do about it

In my diabetes clinic, I’m so often asked by my patients: “Why have I got type 2 diabetes? My friends are all fatter than me and they don’t have this disease.” The answer is this: we all have a different degree of susceptibility to fat. 

Type 2 diabetes is caused by an individual acquiring more fat than they personally can cope with – something I demonstrated in my work as a diabetes researcher a decade ago. When it comes to this illness, there is no one size fits all approach to the question: how fat is too fat?

This week, a study by researchers at the University of Michigan found the number of people around the world who are living with diabetes has more than quadrupled since 1980. Today, almost half a billion people globally have the disease, and 90 per cent of them have the type 2 version. The frightening part is most don’t even realise it.

As someone who has studied type 2 diabetes for many years, these new findings don’t surprise me at all. There’s no mystery surrounding the reason for such an explosion in the condition, which causes the level of sugar in the blood to become too high and can lead to complications such as heart disease and stroke, vision loss and kidney problems: it’s a sickness of modern lifestyles, in which we cook less food from whole ingredients and buy more of it ready-prepared.

But the correlation between type 2 diabetes and obesity is less straightforward than you might think (hence those puzzled patients of mine). Almost three-quarters of those with a BMI of over 45 (in other words, those who are morbidly obese) actually don’t have type 2 diabetes. Meanwhile, 10 per cent of those with the disease have a BMI of under 25, meaning their weight is theoretically healthy. But in the case of these people, crucially, their weight isn’t healthy for them. Our genes determine how much weight each of us can carry before we enter the danger zone, and for some it’s far less than for others.

Our diets have changed dramatically in recent decades. As a result, both men and women are approximately 10kg heavier today than they were 30 years ago. The problem is not the hugely obese people; it’s that most people are walking around with a few extra kilograms they shouldn’t have.

The finger of blame often points towards ultra-processed foods, and rightly so: these foods are designed to fill us up less and leave us craving more. Thirty to 40 years ago, most people were cooking more meals from scratch, and our shift to prepared food has had a disastrous effect.

Exercise plays a part too, of course, but to a lesser degree. If a large man does a good workout, he could still regain all the calories burned by eating some chocolate. Exercise is important for keeping your weight healthy in the long-term, but nothing beats diet when it comes to shedding pounds fast. 

So how do you know if you’re one of the unlucky many who’s walking around without knowing you are diabetic? The short answer is you don’t. This is a disease that creeps up on you silently, not making itself known until it’s well on its way. If you’re passing more urine than usual, feeling thirsty, tired, or succumbing to more skin infections, then yes you should get yourself checked. But by the time these red flags appear, it’s likely the disease has already been present a while. 

It is, however, possible to know if you are at risk before the symptoms appear. If you come from a family with a history of the disease, you stand a fair chance of developing it if your weight goes above a certain level. It’s a genetic predisposition, but it never happens unless a person becomes too heavy for their own body. 

As a rule of thumb, if your waist size is much larger than when you were 21, you are carrying too much fat. Even women who have given birth should be able to get their waist size back to what it was (if not their hip size).  And no, you don’t have to subsist on a lettuce leaf a day. But you do have to watch your portion size, as standard servings today far exceed what the average woman should really consume. 

Men, for their part, get type 2 diabetes at a lower BMI than women. Even if a man is quite slim, an extra layer of belly fat in midlife should be viewed as a warning sign. So-called middle-aged spread should be tackled and not laughed off. 

The risk increases steadily through life and rises sharply after 60. This is partly because the average 60-year-old is larger than the average 20-year-old. But also, as we age, we lose muscle mass. Even a 60-year-old who can proudly say they’re the same weight now as they were at 40 may still be unwittingly at risk, as they’ve probably lost muscle and gained fat.

So what can we do? We must understand that any weight gain after we’ve stopped growing is entirely fat. We can find out what percentage of our body weight is fat by using one of the machines many gyms and pharmacies have, which give you an instant reading. If you’re outside the healthy range (between nine and 20 per cent for men, and between 20 and 32 per cent for women) it’s time to take action. 

But if you do turn out to be one of those walking around without knowing you have type 2 diabetes, take heart in the knowledge it can, in fact, be reversed. The science behind this, which is my area of special interest, is still evolving; but we do know that losing the excess fat you have gained can reduce the fat inside the liver and pancreas that builds up to cause diabetes. The sooner you start, the better, as initial findings suggest that those who have been diabetic for more than 10 years may well struggle to reverse it.

There remains an unfair stigma attached to this illness. Yes, it’s possible to reduce our personal risk; but the failure of governments to regulate the food industry is to blame. The same people who cry “nanny state” at the thought of curbing the market’s ability to make us ill are also the taxpayers picking up the bill for our sickness: more than £10 billion a year is spent on treating type 2 diabetes in England and Wales alone. 

It’s time for us all to wise up and act now to send this trend into reverse. 

As told to Rosa Silverman