The role of diet in managing type 2 diabetes: insights into individualized medical nutritional therapy

In a recent study published in the Antioxidants Journal, researchers investigated the use of medical nutrition therapy for type 2 diabetes mellitus (T2DM) patients.

Study: Comprehensive Approach to Medical Nutrition Therapy in Patients with Type 2 Diabetes Mellitus: From Diet to Bioactive Compounds. Image Credit: Chinnapong/Shutterstock.com

Background

Diet is a significant factor in the development of T2DM. Medical nutritional therapy is crucial in managing T2DM and can improve metabolic outcomes as part of lifestyle optimization. Supplementation with antioxidants, including carotene, vitamins C and E, and other micronutrients, has no proven benefits due to inconsistent evidence regarding their efficiency and long-term safety.

Studies indicate that nutraceuticals may have positive metabolic effects in individuals with T2DM; however, further evidence is required to determine their safety and effectiveness.

Medical Nutritional Therapy

Medical nutritional therapy is important for managing T2DM. The American Diabetes Association (ADA) 2022 endorses the following goals for nutritional therapy:

• Encourage healthy eating habits and portion control while considering individual requirements and cultural and personal preferences.
• To promote enjoyable eating habits while avoiding foods linked to negative health outcomes.
• To equip patients and caregivers with useful resources for attaining a healthier eating routine and enhancing their diet's overall quality.
• To highlight that the nutritional goals for T2DM patients are comparable to those advised for the general population.

Macronutrients

Managing T2DM involves controlling postprandial and fasting glycemic levels, which can be achieved by focusing on carbohydrate intake. T2DM patients typically consume a moderate carbohydrate content. Reducing carbohydrate intake with a low or very low carbohydrate diet has been proven to be a viable method for individuals with T2DM to enhance their blood sugar levels.

A meta-analysis of 23 studies found that a low- and very-low-carbohydrates (CHO) diet for six months improved HbA1c levels and fasting glucose levels in T2DM patients.

Patients on the experimental diet showed greater weight loss, decreased diabetes medication usage, improved triglyceride levels, and insulin resistance compared to those on control diets.

Nutritive sweeteners

Limiting or avoiding sugar-sweetened beverages and processed foods is recommended for T2DM patients to lower the risk of weight gain and increase the cardiometabolic risk profile. Consuming fructose at doses greater than 60 g/day or over 10% of energy instead of other carbohydrates can increase serum triglyceride levels in T2DM patients.

A meta-analysis found that high doses of fructose consistently raised triglyceride levels across various subject types. Replacing fructose with other carbohydrates in short-term controlled feeding trials improved glycemic control in T2DM patients, resulting in a reduction of approximately 0.53% in hemoglobin A1c (HbA1c) without impacting insulin levels.

Fats

Fat and saturated fatty acids (SFAs)

T2DM patients should follow the same SFA intake guidelines as the general population. Limit SFAs intake to 10% of total daily calories and replace them with unsaturated fats, especially polyunsaturated fatty acids (PUFAs). A high intake of SFAs has been linked to an increased risk of cardiovascular disease.

Replacing SFAs with PUFAs leads to a notable reduction in total cholesterol and low-density lipoprotein (LDL)-cholesterol. Substituting SFAs with plant-based monounsaturated fatty acids, such as olive oil and nuts, can lower the risk of cardiovascular disease.

Trans fatty acids

Studies indicate that consuming more industrial trans fatty acids is linked to an increased risk of cardiovascular disease. Industrial trans fatty acids (TFAs) have a stronger atherogenic effect than SFAs or cis-unsaturated fatty acids.

TFAs increase total and LDL-C concentrations while reducing high-density lipoprotein (HDL)-C concentrations.

A meta-analysis of seven randomized controlled trials found that consuming trans fatty acids did not have a significant impact on insulin and glucose levels. However, increased trans fatty acid consumption was associated with a notable elevation in total and LDL cholesterol.

Monounsaturated Fatty Acids (MUFAs)

MUFAs can enhance insulin sensitivity by reducing endoplasmic reticulum (ER) stress and exhibiting anti-inflammatory properties. They improve β cell survival and prevent the decline of the insulin signaling pathway.

A review of 24 randomized controlled trials found that diets high in MUFAs may benefit T2DM patients by improving metabolic factors such as glucose and insulin levels, insulin resistance, beta-cell function, HDL cholesterol levels, and triglyceride levels.

Micronutrients

Studies have found no evidence to support the routine use of antioxidants, like carotene, or vitamins E and C, for individuals with T2DM, despite the condition being linked to higher levels of oxidative stress. This is due to a lack of demonstrated effectiveness and long-term safety.

Furthermore, scientific proof does not support using micronutrients and herbal supplements routinely.

Conclusion

The study findings showed that scientific evidence does not support the prescription of a specific macronutrient distribution for meal plans. Therefore, it is recommended that meal plans be personalized to meet individual needs.

Replacing high glycemic index (GI) foods with low GI foods and reducing overall carbohydrate intake are effective options for T2DM patients to enhance glycemic control.

Additional research is required to assess the effectiveness and safety of antioxidant supplementation and nutraceuticals in individuals with T2DM.

Written by

Bhavana Kunkalikar

Bhavana Kunkalikar is a medical writer based in Goa, India. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. Her educational background allowed her to foster an interest in anatomical and physiological sciences. Her college project work based on ‘The manifestations and causes of sickle cell anemia’ formed the stepping stone to a life-long fascination with human pathophysiology.