Type 2 Diabetes (T2DM) and plant based diets

1 in 15 people in the UK have T2DM (more than doubled over the last 20 years) and it’s predicted by 2030 that 5.5 million people could have T2DM in the UK with an annual cost of treating it reaching £16.9 billion by 2035 – that’s 17% of the entire health budget of the NHS!

The main contributing factor of T2DM is being overweight/obese. The number of fat cells in our bodies remain fairly constant throughout adulthood; they shrink with dramatic weight loss and stretch with weight gain but when they are stretched too much with excessive saturated fat consumption, the fat over spills into our bloodstream. It becomes lodged inside our muscle cells which leads to insulin resistance and promotes the onset of T2DM. It’s important to note that this can also happen to a slim person if they have a high fat diet. A slim person usually has 10-50 micromoles of free fat circulating in their blood stream at any one time. Those who are overweight/obese have about 60-80 micromoles but the higher end can easily be reached by a slim person on a high fat diet.It is much better to adopt healthy eating patterns before there is a risk of developing T2DM but if a person has been diagnosed, can a whole food plant based diet actually reverse T2DM?

Let’s look at the benefits of plant based diets and T2DM: 

1. High fibre content: fibre reduces the energy density of food, promotes fullness (satiety) and has been associated with maintaining a more healthy weight thereby improving insulin sensitivity. It can help maintain blood glucose levels and is fermented by our gut bacteria to produce short chain fatty acids (SCFAs). These have many functions including improving glucose response/insulin signalling/insulin sensitivity and favourably affecting gut hormones that regulate our appetite thereby controlling our food intake and helping us maintain a healthy weight. 

2. High levels of phytonutrients and antioxidants: micronutrients called polyphenols, which are high in antioxidants, may stimulate insulin secretion, enhance glucose uptake into the cells (reducing blood glucose) and reduce liver glucose output

3. Low levels of saturated fat: over time, high levels of sat fat in our diets can increase oxidative stress which leads to inflammation and can induce complications of diabetes including stroke, neuropathy and kidney problems. Saturated fat from palmitate (palm oil and animal products) has been shown to be directly toxic to pancreatic beta cells (cells that produce insulin); the same doesn’t apply to oleate (primarily from nuts, seeds and avocado).

4. Certain plant foods have a low Glycaemic Index (GI): GI is a measure of how quickly a food can make your blood glucose (BG)rise and runs from 0-100. In general the more cooked/processed the food the higher its GI and the more immediate its effect on your BG levels and the higher fibre/fat content the lower its GI (under 55). The fat content means some lower GI foods may not be the healthiest choice (eg chocolate) so these foods shouldn’t be eaten regularly. Research has shown that choosing healthy, low GI foods can help manage long term BG levels. These include oats, whole wheat bread, hummus, cashews, grapes and soya milk.

There have been many studies on the benefits of a plant based diet and T2DM – too many to go into detail here but below are two significant studies:

One published in 2006 was carried out by Dr Neal Barnard who split 100 subjects (randomly assigned) into two groups. 1 followed the standard American Diabetes Association Diet and the other a whole food plant based diet. Both groups managed to reduce their diabetes medications (43% of vegan group, 26% ADA group) although the vegan diet was more effective at lowering cholesterol and overall BG levels.

Another study published in 2018 by Kahleova et al took 2 groups of overweight individuals and randomised them to follow a plant based or control diet containing animal protein. The results showed that the vegan diet was associated with improved body weight, fat mass and insulin resistance markers. 

So, in summary, the evidence that is currently available shows that following a whole food plant based diet can result in improvements in all the causal factors of T2DM, including weight, fat mass, insulin resistance, balance of gut hormones and reduced oxidative stress. This is certainly an exciting area of research to keep a very close eye on.