Can the Mediterranean diet prevent diabetes?

Can the Mediterranean diet prevent diabetes?

OUR DIABETES WA HEALTH TEAM BREAKS DOWN THE LATEST STUDIES AND FINDINGS TO HELP YOU UNDERSTAND WHAT’S HAPPENING IN THE WORLD OF DIABETES SCIENCE.

A new study suggests that low-GI foods can enhance the positive effects of a healthy, Mediterraneanstyle diet for people at risk of type 2 diabetes, writes JESSICA WEISS

We know that better understanding around food choices has a massive impact on diabetes management. Those who are newly diagnosed with diabetes often need help to become aware of how certain foods affect their blood glucose levels.

One helpful measure is the glycaemic index (GI), which can help determine how much a particular food will make your blood glucose levels rise. A number of factors influence the GI of a food, including its nutrient composition, how it was cooked, how ripe it is, and how processed it is. Generally speaking, foods with a low GI raise blood glucose levels (BGL) less dramatically than foods with a high GI. The measure of BGL after eating is sometimes referred to as postprandial (or “after eating”) glucose. A new study shows that, even when eating an otherwise healthy diet, people at risk of developing type 2 diabetes have much to gain from avoiding high GI foods. It is thought that postprandial glycaemia – or a high BGL after eating – may be a cause of the insulin resistance we see in people at risk of developing type 2 diabetes. As yet, there has been little study into whether incorporating low GI foods as part of a healthy diet to avoid BGL spikes can help with prevention of developing type 2 diabetes. There is, however, an impressive amount of evidence that the Mediterranean diet (see our previous issue for details) is associated with a reduced risk of developing type 2 diabetes – even if most of that evidence is observational, rather than laboratory tested. The main health-giving benefits of that eating style are thought to be the sort of fats, the nature of the fibre and certain bioactive compounds the diet contains. The diet also tends to be comprised of low-GI foods, although the relative health benefits importance of the low-GI elements was not known.

The new study examined the impact of a low-GI vs high-GI Mediterranean diet on blood glucose management among people at risk of developing type 2 diabetes. Those running the study expected to find the low-GI group of participants would experience lower postprandial BGL spikes and improved BGL management overall, compared to participants following a high-GI diet. Over 12 weeks, subjects consumed a controlled diet that was either high- or low-GI. During those weeks, the average postprandial insulin surge and BGL reading was greater for those consuming the high-GI diet, which was as expected. What was unexpected was that any improvement in either of these measures for those on the low-GI diet disappeared in the weeks after the study finished, although those on the high-GI diet continued to have higher-than-usual postprandial glucose. The greatest differences between the two groups in terms of insulin and BGL were observed at lunch. The authors of the study have concluded that consuming a Mediterranean eating style comprised of low-GI foods can lead to a measurable reduction in glucose levels after meals for people at risk of type 2 diabetes. However, any improvement in terms of postprandial insulin release appeared to disappear once the study finished, meaning that there was no lasting benefit if people didn’t keep up with the low-GI diet. There was also no measurable improvement on fasting glucose, Oral Glucose Tolerance Test (OGTT) or HbA1c on the low-GI cohort, which was not considered surprising. Given that only the low-GI version of the diet produced improvements in blood glucose variability, it appears that its focus on low-GI foods may indeed be one of the reasons that adopting the Mediterranean diet seems to bring numerous health benefits to those with, those without or those at risk of developing type 2 diabetes.