New Studies Affirm Mediterranean Diet's Potential for Patient Self-Management, Prevention of T2DM

Published Online: March 17, 2014
Surabhi Dangi-Garimella, PhD
Diet control, over and above a healthy and active lifestyle, has always been recommended for hyperglycemic individuals. A diet rich in vegetables, whole grain, fruits, lean meats, fish, and low in high-fat, highsugar, and processed foods could help prevent disease incidence and also help diabetics better manage their condition. The Mediterranean diet (followed by countries bordering the Mediterranean Sea) includes most of these listed food types and has been gaining increasing approval, especially following recent clinical trials that reaffirmed the benefits of this diet. In addition to being plant-based and low in dairy, the Mediterranean diet includes beans, nuts, and legumes and primarily uses olive oil (poor in saturated and trans fats) for cooking (Figure 1). Additionally, the diet is low in saturated animal fats and provides for moderate fish intake, the source of polyunsaturated fats. This dietary pattern has been associated with benefits regarding cardiovascular riskfactors such as obesity, hypertension, diabetes, and metabolic syndrome.

A subgroup analysis of a trial conducted in Spain among older adults (men and women) at high cardiovascular risk who were assigned to 1 of 3 dietary groups (control with reduced fat intake, Mediterranean diet supplemented with nuts, or Mediterranean diet supplemented with extra-virgin olive oil, or EVOO) found that supplementing with EVOO reduced the risk of diabetes after a 4-year follow-up. Fewer individuals in the Mediterranean diet groups developed type 2 diabetes mellitus (T2DM) than in the control groups. This trial primarily considered the implications of dietary modifications, without any intervention to increase physical activity or lose weight.3

A study published in the journal PLoS One evaluated the effect of dietary pattern in a non-Mediterranean and occupationally active young population, in this case a group of male firefighters. Unlike previous studies conducted primarily in older, Mediterranean cohorts, this study involved subjects in the United States who might not naturally choose a Mediterranean diet. In the absence of dietary intervention, the researchers developed a modified Mediterranean diet score (mMDS) to assess preexisting dietary habits. Obese subjects (high fast food and sweetened drinks intake) had lower mMDS scores and higher mMDS scores were found inversely correlated to risk of weight gain over a 5-year period. The study concluded that participants who adhered to the Mediterranean-style diet presented lower weight gain, LDL-cholesterol, and metabolic syndrome and a higher HDL-cholesterol. However, the authors recognized several deficits in their study, such as the absence of certain major dietary components (nuts, legumes, wine, and ocean fish); this limitation was a result of the population being examined. Based on the proven effectiveness of this diet, the authors are planning further intervention studies.2

Disease Facts

Diabetes is defined as a fasting plasma glucose (FPG) ≥126 mg/dl, A1C ≥6.5%, and/or oral glucose tolerance test (OGTT) 2-h plasma glucose ≥200 mg/dl.1 A metabolic disorder characterized by progressive hyperglycemia, declining beta-cell function, and reduced sensitivity to insulin, type 2 diabetes mellitus (T2DM), also known as insulin-dependent diabetes mellitus, is the most common form of diabetes. In patients suffering from T2DM, there is either a dearth of or resistance to insulin, subsequently resulting in increased blood glucose levels. As a consequence, the cells are energy-deprived and the longterm effects of this phenomenon may result in harmful effects to the heart, eyes, kidneys, or nerves.1,4

Disease symptoms include frequent urination, thirst, hunger despite eating, fatigue, slow-healing wounds, tingling or pain in the extremities. As of early 2011, 8.3% (25.8 million) of the US population was estimated to suffer from diabetes, of which 7 million were predicted to be undiagnosed, 25.6 million were predicted to be ≥20 years old and 10.9 million were over 65 years old.

Among the 20 years and older population, no significant gender bias was noted.1

T2DM is associated with severe morbidity and mortality, with 71,382 deaths directly associated with the disease in 2007, and 160,022 deaths in which diabetes was a contributing factor. As noted earlier, the long-term effects of T2DM affects several different organs that can result in cardiovascular disease, stroke, high blood pressure, blindness, kidney disease, neuropathy, and amputations.1

Comorbidities and Treatment-Associated Risks

Two major issues with disease management include the increased cardiovascular morbidity and mortality associated with the disease and the lack of therapies with efficient glycemic control without long-term adverse effects.4 Studies have shown a 2-fold increase in cardiovascular disease in the T2DM population and about 66% of patients have been shown to die following coronary heart disease or stroke, despite attempts at risk management with lifestyle changes (such as smoking cessation) and treatments.

Studies conducted to answer some of these questions found that exogenous insulin treatment was safe in newly di-agnosed T2DM patients monitored for over 6 years, which allayed previously raised concerns about cardiovascular disease and cancer.5 Another study concluded that intensive therapy with insulin and metformin or a triple oral therapy (metformin, pioglitazone, glyburide) after an initial treatment period with insulin can help preserve beta-cell function over 3 years.6

Economic Outcomes

For the year 2012, the total cost of treating diagnosed diabetes was projected at $245 billion ($176 billion direct medical costs and $69 billion indirect), with hospital inpatient care, prescription medicines, and physician visits being the major contributors to the direct costs. Indirect costs of the disease include absenteeism, reduced productivity at work, disability costs, etc.1

Lifestyle changes, such as changing or improving dietary patterns, could substantially influence disease outcome and slash the costs associated with disease management. However, food choices are primarily driven by financial restrictions, resulting in a greater intake of caloric- and energy-rich foods.

A study recently published by a research group in Italy reviewed published literature to analyze the cost-effectiveness of adherence to a Mediterranean diet and the prevention of degenerative pathologies by evaluating the economic performance of the diet.7 Although most of the studies evaluated were conducted in the Mediterranean countries, a study conducted in a US population cohort concluded that although the diet recommends high-value food items such as vegetables, nuts, fruits, legumes, poultry, fish, and olive oil for cooking, the reduced dietary costs of red meat, desserts, sweets, and fast food could balance the equation. Overall, the various studies reached a consensus that the socioeconomic gradient drives dietary patterns, and economically challenged populations seem to suffer most from chronic conditions such as obesity, diabetes, and cardiovascular disease.7 The authors who conducted the review called for conducting more studies that link food cost to diet adherence for various dietary patterns, the results of which could help frame policies to improve dietary adherence among prediabetics and diabetics.

A collaborative study between Lehigh University and the US Department of Agriculture’s Economic Research Service, published back in 2010 in the American Journal of Agricultural Economics, evaluated the impact of low- and high-carbohydrate foods on the prevalence and medical costs of diabetes. The study proposed the use of subsidizing the cost of low-carbohydrate foods to improve the health of diabetics, which they concluded was more effective than taxing high-carbohydrate foods like soda. Additionally, insurer-initiated enrollment of patients with diabetes in disease management programs, which has already been introduced by payers, could serve as a means of subsidy interventions.8

Disease prevention would definitely prove more economical than disease management, as shown in the 2 trials discussed above. Preventing diabetes in adults 65 years and older would be a tremendous cost-saving for the society and the healthcare system. Several different studies have presented the cost-effectiveness of preventing diabetes and form the basis of the Preventing Diabetes in Medicare Act (2011), which has a provision for Medicare to provide medical nutritional therapists to prediabetics or patients at risk of diabetes, as well as for diabetics.9

Incentives to Improve Patient Self- Management of the Disease

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