Diabetes Prevention with Mediterranean Diets

by | Jan 27, 2016 | 2014, Diabetes, Mediterranean Diet, Pancreatic Health

Written by Marcia J. Egles, MD. A Mediterranean diet supplemented with 50ml of extra-virgin olive oil can reduce the risk of diabetes.

With a worldwide prevalence more than doubling in the past thirty years, type 2 diabetes mellitus continues to grow as a mammoth health burden (2). Despite compelling evidence that lifestyle changes might halve the incidence of this disease, the problem continues to worsen (3). A new study from Spain demonstrates that even without lifestyle changes such as weight loss or exercise, the implementation of a Mediterranean diet enriched with olive oil, reduced the diabetes risk among older adults with cardiovascular risk factors (1).

Mediterranean-style diets are rich in fruit, vegetables, nuts, legumes, unrefined grains, and fish, with olive oil as its main source of fat. Although low in saturated fats, Mediterranean diets are moderately rich in vegetable fats and fish oil, with fat accounting for 35-40% of the total calories. Sauces with tomato, onions, garlic, and spices are typically used. Red wine is consumed with meals in small to moderate quantities. Red and processed meats, butter and sweets are eaten in minimal amounts (2). Several studies and clinical trials during the past decades have associated the traditional Mediterranean diet with a lower incidence of heart disease and some types of cancer, as well as an association with decreased diabetes (3, 5, 6).

As a part of the ”Prevencion con Dieta Mediterranea” study (PREDIMED), 3541 men and women aged 55 to 80 who were at high cardiovascular risk but without diabetes were recruited from 11 medical centers throughout Spain. These Mediterraneans were community-dwellers with at least three risk factors for cardiovascular disease. The cardiovascular risk factors included ongoing tobacco use, hypertension, high cholesterol, and overweight or obesity.

At the start of the study, the patients were randomly assigned to one of three diets: 1154 participants to a Mediterranean diet supplemented with 50 ml of extra-virgin olive oil (EVOO) per day, 1147 to a Mediterranean diet plus 30 grams of mixed nuts (walnuts, almonds,hazelnuts) per day, and 1240 to a low-fat control group diet. The patients received instructions for their respective diets by dietitians. Neither caloric restriction nor increased physical exercise was advised for any intervention group.

The participants were followed on average for four years. In the Mediterranean diet/ EVOO group, 80 persons developed diabetes (Rate of 16.0 cases per 1000 person years, p=0.05). In the Mediterranean diet/ mixed nuts group, 92 persons became diabetic (18.7 case rate, p=0.05). The control group with the low-fat diet had 101 new diabetics (23.6 case rate, p=0.05). Changes in body weight, waist circumference and physical activity were minor did not differ by diet group.

A Mediterranean style diet might be considered a fairly easy, palatable and sustainable choice with beneficial public health implications as the study’s authors observe. While any improvement is helpful, many of people in all three groups in the study still were developing diabetes. The more difficult interventions of exercise and the achievement of a normal body weight might offer additional diabetes prevention. For older adults considering the advantages of a Mediterranean diet as compared with a low-fat diet, this study adds to the evidence in favor of a Mediterranean diet and the use of olive oil. 

Source: Salas-Salvadó, Jordi, et al. “Prevention of Diabetes With Mediterranean DietsA Subgroup Analysis of a Randomized Trial.” Annals of internal medicine 160.1 (2014): 1-10. 

 © 2014, The American College of Physicians

Posted February 27, 2014.

References:

  1. Salas-Savado, Jordi Prevention of Diabetes with Mediterranean Diets. A Subgroup Analysis of a Randomized Trial.  Annals of Internal Medicine, 2014, 160: 1, pp. 1-10.
  2. Danaei  G. et al.: Global Burden of Metabolic Risk Factors of Chronic Diseases Collaborating Group (Blood Glucose).National, regional ,and global trends in fasting plasma glucose and diabetes prevalence since 1980:systematic analysis of health examination surveys and epidemiological studies with 370 country-years and 2.7 million participants. Lancet. 2011; 387: 31-40.
  3. Gillies CL, et al. Pharmacological and lifestyle interventions to prevent or delay type 2 diabetes in people with impaired glucose tolerance: systemic review and meta-analysis. BMJ. 2007: 334:299.
  4. Willett WC; Sacks, F; Trichopoulou, A; Drescher, G; Ferro-Luzzi, A; Helsing, E; Trichopoulos, D (June 1, 1995). “Mediterranean diet pyramid: a cultural model for healthy eating”. American Journal of Clinical Nutrition 61 (6): 1402S–6S. PMID 7754995.
  5. Estruch R, Ros E, SLAS-Salvado J, et al: PREDIMED Study Investigators. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013: 368:1279-90.
  6. Giacosa A, Barale R, Bavaresco L, Gatenby P, Gerbi V, Janssens J, Johnston B, Kas K, La Vecchia C, Mainguet P, Morazzoni P, Negri E, Pelucchi C, Pezzotti M, Rondanelli M Cancer prevention in Europe: the Mediterranean diet as a protective choice. European Journal of Cancer Prevention 2013 Jan;22(1):90-5. doi: 10.1097/CEJ.0b013e328354d2d7.