Reversal of Type 2 Diabetes Investigated

A new study using rats has revealed why weight loss surgery can reverse Type 2 diabetes.

Last year, Diabetes UK reported that almost 4 million people in the UK are living with diabetes. Around 90% of these cases are classed as Type 2, which is often caused by obesity.

Interestingly, cases of Type 2 diabetes have been reversed in patients undergoing weight-loss surgery, with some patients leaving hospital after only a few days, no longer needing to take their diabetes medication. Studies have shown that it’s the low calorie diet that follows the surgery, rather than the surgery itself, that is responsible, however the possible causes have remained a mystery. 

Now, a study in the journal Cell Metabolism has measured the biological mechanisms by which the reversal of Type 2 diabetes is made possible, by giving diabetic rats a low calorie diet.

“Blood sugars are high, in part, because the liver makes too much glucose in diabetes," explains Rachel Perry, a member of the team that performed the study at Yale University. "This process is improved with caloric restriction and we found that the glucose-lowering effect of caloric restriction occurs because of reductions in three pathways that contribute to high blood sugar."

These three mechanisms include reducing the breakdown of glycogen, which is the short-term storage form of glucose, lowering the synthesis of new glucose and lowering fat accumulation in the liver. 

The team was surprised that the lowering of blood sugar levels in the rats occurred before any significant weight loss was observed, although they believe weight loss would have eventually occurred if the rats had stayed on their low calorie diet for longer.

The next stage of the study is to observe the effects of the same caloric restriction in humans. If the findings are replicated, it could become possible to treat and reverse Type 2 diabetes with either a restricted calorie diet or with new drugs.

“One of the main benefits of this study is that it identifies molecular pathways by which caloric restriction leads to a reversal of diabetes. In theory, you could do it by diet or by targeting any of the three, or better yet all of the three, pathways that we found in this study," says Perry, adding that “I think that interventions based on reducing liver fat content, and thereby improving liver-insulin responsiveness, are going to be the way to go.”