Remission of Type 2 Diabetes With Mediterranean Diet, Physical Activity and Psychological Support: a Randomized Clinical Trial

Type 2 diabetes (diabetes mellitus type 2, DM2) is a leading clinical and public health problem, with a global prevalence that is rapidly increasing and reaching pandemic proportions. According to the International Diabetes Federation (IDF), 537 million adults between the ages of 20 and 79 in the world have type 2 diabetes (DM2), and it is predicted that this number will increase to 643 million by 2030 and 783 million by 2045. According to the data of the National Register of Persons with DM2 (CroDiab) 337,774 persons with DM2 type 2 were registered in Croatia in 2022.

DM2 increases the risk for cardiovascular diseases, blindness, kidney failure and amputation of the lower limbs, thereby significantly affecting the quality of life of the patients. Additionally, it is well known that people with DM2 often have obstructive sleep apnea (OSA). Therefore, active screening for an OSA diagnosis and its treatment in patients with DM2 is extremely important for the prognosis and successful treatment of DM2, especially since it has been shown that CPAP treatment, along with body weight reduction, is associated with a reduction in HbA1c in morbidly obese patients with severe OSA.

The increased prevalence of DM2 is inextricably linked to the change in lifestyle and the transition to a "western" lifestyle, which implies an abundance of energy-rich foods and reduced physical activity, with a subsequent increase in obesity. Looking at individual components of the diet, it has been shown that sweetened beverages, refined grains and processed meat increase the risk of developing DM2. On the other hand, green leafy vegetables, dairy products, whole grains, nuts, legumes, moderate amounts of alcohol and coffee are associated with a reduction in this risk. Considering not only the individual nutrients in the diet but the entire nutrition pattern, the Mediterranean diet stands out with its numerous protective effects on the health of the organism. Epidemiological and interventional studies have shown the protective effect of the Mediterranean diet in chronic inflammation, insulin resistance, and metabolic syndrome. The Mediterranean diet is best known for its protective cardiovascular effect, which has been shown in a number of studies, meta-analyses and systematic reviews. Among other things, this type of diet supports healthy aging (reaching the age of 70 and over without chronic diseases, such as DM2, kidney disease, respiratory diseases, cancer or Parkinson's disease, and without significant decline in mental and cognitive function).

Losing excess body weight is a key factor in achieving remission of DM2, therefore it is important to look at the evidence of how different dietary patterns can promote weight loss. Comparing low-carbohydrate, low-fat, and Mediterranean diet showed that both the Mediterranean diet and the low-carbohydrate diet were superior in achieving weight loss compared to the low-fat diet. Moreover, these two dietary patterns also showed significant metabolic benefits, such as reduced CRP, reduced fasting glucose and increased insulin sensitivity. In the PREDIMED study, it was shown that a Mediterranean diet supplemented with nuts or extra virgin olive oil reduces the risk of death from stroke by 30%. In addition, there was a significant reduction in the incidence of DM2 in subjects on the Mediterranean diet, independent of weight loss or the subjects' physical activity. Hence, besides weight loss, the quality of nutrition is a valuable factor in the prevention of DM2. The Mediterranean diet is based primarily on unprocessed food of plant origin (vegetables, fruits, legumes, whole grains, nuts). Moderate consumption of fish, seafood and dairy products is encouraged, as well as avoiding red and processed meat. The main source of fat in the Mediterranean diet is extra virgin olive oil. Apart from water as the main drink, wine can be enjoyed in moderation with a meal.

DM2 is considered to be an incurable, chronic and progressive disease. However, several studies recently showed that it is possible to achieve a remission of the disease. It is considered that the remission of DM2 has been achieved if Hba1c is less than 6.5%, without the use of blood glucose-lowering drugs for at least 3 months. Body weight control is the most important aspect of DM2 treatment, with weight reduction leading to reduced morbidity and mortality in these patients. The results of several studies have shown that weight loss of at least 10-15 kg leads to normalization of blood glucose levels in people who were relatively recently diagnosed with DM2. The DIRECT study showed that an intensive and structured weight management program delivered in primary care can result in significant weight loss and diabetes remission among adults with newly diagnosed diabetes. Remission of DM2 was achieved in 46% of subjects who lost an average of 10 kg, after one year. After two years, 36% of subjects were still in remission, with an average of 8 kg lost.