What is type 3 diabetes?

Experts have identified a new kind of diabetes, type 3, as a cause of dementia. Health writer Stephanie Osfield explains how to protect yourself.

Have you ever noticed how foggy your thinking gets if you haven’t had a chance to eat all day? Just as a car needs petrol, your brain relies on a form of sugar called glucose as its main source of fuel. And although your brain makes up approximately two per cent of your body weight, it uses a massive 20 per cent or more of your body’s glucose supply.

But if your diet is not brain friendly and as healthy as it could be, you may risk developing problems related to using that fuel efficiently. Over time, in some people, this can trigger a condition being called ‘type 3 diabetes’, which is also known as ‘diabetes of the brain’.

Though it’s not yet used by all doctors, the term ‘type 3 diabetes’ has now been recognised in research. And it may soon be used when diagnosing dementia.

“Some researchers already use it to describe cases of alzheimer’s where the main cause appears to be the brain losing its ability to efficiently use glucose for energy,” explains professor Merlin Thomas from the department of diabetes at Monash university. “This can cause a progressive reduction in memory, reasoning, judgment and insight.”

So, what is insulin?

Think of insulin as a key. Its job is to open the doors that allow glucose to move from your bloodstream into your muscles and cells, where it can then be used as energy.

Insulin and your brain

The changes caused by type 3 diabetes occur due to the development of insulin resistance in the brain.

“Insulin moves glucose out of the blood and into your cells, where it’s used for energy,” says Ngaire Hobbins, a dietitian specialising in nutrition, brain health and dementia, and author of Better Brain Food. Diabetes causes glitches in this powering-up process.”

“In type 1 diabetes the immune system destroys the cells that make insulin,” Hobbins explains. “In types 2 and 3, your body becomes less sensitive to insulin.” This happens when your blood glucose levels keep running too high for too long.

One of the results is that not enough glucose is able to move from your blood to your brain to power up those brain cells.

Could you be at risk?

A particular gene can make some people particularly vulnerable to developing type 3 diabetes.

According to research from the Mayo Clinic, about 20 per cent of people carry the gene and 50 per cent of alzheimer’s cases can be linked to it. Researchers have also investigated whether using a nasal spray containing insulin might help people with suspected type 3 diabetes — and early results have shown this may prove a promising treatment. But for prevention, a healthy lifestyle is the best approach.

How to look after your brain

Lifestyle factors that keep your heart healthy and reduce type 2 diabetes risk can also help to protect your brain against type 3 diabetes. So, it pays to adopt these healthy habits early on…

1. Choose food your brain will love

   Load up on veges
   “At meals, aim for your plate to be at least half filled with vegetables of many colours,” Hobbins advises. “Foods that boost healthy gut bacteria also benefit your brain. So add some fibrous prebiotic vegetables such as asparagus, beetroot and peas to the mix, as well as probiotic fermented veges like sauerkraut and kimchi.”

   Cut back on fats
   “In recent years the focus on sugar and carbs has meant people can often forget that high fat levels can also increase insulin levels and insulin output,” says associate professor Neale Cohen, the director of Clinical diabetes at the Baker IDI Heart and diabetes institute. “This is because the beta cells (which produce insulin in the pancreas) also have fat receptors.”

   The take-home message from this? One is to eat lean protein such as fish, and chicken without the skin, and minimise your intake of saturated fats from foods such as butter and red meat. Enjoy a variety of good fats from nuts, seeds, olives and oily fish. “Fish contains healthy omega-3 fatty acids that help your brain use glucose more effectively,” Hobbins says.

   Get smart about carbs
   Choose foods that are high in fibre and have a low-glycaemic index (GI), because these foods will give you a slower, sustained release of energy. Good choices include wholegrain bread, oats, brown rice, quinoa, beans and lentils. And according to the Glycemic index Foundation, vinegar, yoghurt and lemon juice can also be added to foods to help lower their GI.

2. Move more and differently
   

   “Exercise makes every cell more sensitive to insulin, meaning that glucose enters your cells more easily,” says Christine Armarego, exercise physiologist.

   “Twenty-four hours after you work out, your insulin sensitivity peaks. Within 48 hours it has returned to what it was.” That’s why daily exercise is best to keep insulin sensitivity at its highest. “If you can’t manage that, try not to let more than 48 hours pass between exercise sessions,” Armarego advises.

   Exercise makes every cell more sensitive to insulin, meaning that glucose enters your cells more easily

3. Watch your waistline
   

   As weight creeps up, so does insulin resistance. “If you are overweight, losing just 5–10 per cent of your body weight can greatly improve your sensitivity to insulin,” Cohen says.

   It’s also important to measure your waist. If it measures more than 80cm (for women) or 94cm (for men), then you’re more likely to have a problem with insulin resistance.

4. Make more time for sleep
   

   New research from the university of Chicago shows insulin resistance can start to occur after only four nights of sleep being cut back to 4.5 hours a night. The upshot? Aim for at least seven or eight hours of sleep nightly and skip the late-night Netflix binges.

5. Take charge and keep cool
   

   Stress causes your body to begin releasing stress hormones such as cortisol and adrenalin. These disrupt the ability of cells to get the glucose and energy they need from your blood and may also lead you to store more fat around the abdomen. That can be bad news for your belly and your brain. So, address your stress. Find out about calming practices such as slow breathing, meditation and mindfulness. Try regular nature excursions to reduce stress hormones and help you feel more relaxed.