By Lauren Boyd, Desiree Udarbe & Sarah Peterson

By Lauren Boyd, Desiree Udarbe & Sarah PetersonThe Effect of a Vegan/Vegetarian Diet on Diabetes and Insulin Resistance

The Effect of a Vegan/Vegetarian Diet on Diabetes and Insulin ResistanceApproximately 90 to 95% of all diagnosed cases of diabetes are type 2 diabetes mellitus (T2DM)

Prevalence of T2DM increases with age and is being diagnosed increasingly in children and adolescents

factors that increase the risk of developing T2DMObesityfamily history/history of gestational diabetes mellitusimpaired glucose metabolismphysical inactivity

How T2DM different from Type 1 Diabetes Mellitus?Type 1 diabetes mellitus develops from a lack of insulin due to the destruction of beta cells in the pancreas

T2DM results when individuals are producing insulin but their tissues are resistant to the insulin.

This type of insulin resistance causes the pancreas to increase production of insulin. Over time, the pancreas loses its ability to produce insulin and consequently, causes metabolic defects in the individual.

Insulin resistance and relative insulin deficiency are two common defects observed in individuals with T2DM.

Causes Of Insulin Resistance in T2DMInsulin resistance is caused by a cell-receptor defect.

This defective insulin secretary response results in a surplus of glucose production from the liver since insulin is responsible for inhibiting gluconeogenesis and glycogenesis when blood glucose is high.

In T2DMFirst, postprandial glucose levels increase Then, hepatic gluconeogenesis responds to the lack of glucose and the response causes fasting hyperglycemia.

Insulin resistance is caused by a cell-receptor defect that alters the bodys ability to utilize insulin incorrectly. Cells that cannot react to insulin, by translocating glucose transporters to outer membranes, are unable to use glucose from the blood for energy.

First, postprandial glucose levels increase due to the inability of the cells to take up glucose. Soon after, hepatic gluconeogenesis responds to the lack of glucose and the response causes fasting hyperglycemia.

Conventional Treatment For T2DMT2DM is conventionally treated by observing three factors that play a role is glycemic control:Hepatic glucose productionGlucose uptake by the periphery Absorption of glucose from food

Medical therapy of T2DM emphasizes nutrition therapy, physical activity and use of medications to normalize glycemic control.

Use of medications for T2DM is only observed in individuals who cannot accomplish glycemic control through nutrition therapy and physical activity.

Achieving glycemic control involves controlling blood glucose.

Conventional Treatment Goals For T2DMAccording to Nutrition Therapy Guidelines, to promote a lifestyle for the patient that will result in better metabolic control.

Conventional nutrition intervention for T2DM involves:moderate weight loss for individuals with BMIs>25 kg/m2 monitoring total grams of carbohydratesassuring protein intake does not exceed 20%assuring fat intake is less than 25-35% of total kcal less than 7% of fat from saturated fatincreasing fiber intake.

According to studies, fiber decreases the rate of absorption of glucose from the small intestine, resulting in a positive effect on serum glucose levels

Guidelines enforce monitoring total grams of carbohydrates because it is an accurate predictor of glycemic response and a strategy to help achieve improved glycemic control.

Treatment goals, according to nutrition therapy guidelines, are to promote a lifestyle for the patient that will result in better metabolic control. Conventional nutrition intervention for T2DM involve moderate weight loss for individuals with BMIs>25 kg/m2 , monitoring total grams of carbohydrates, assuring protein intake does not exceed 20%, assuring fat intake is less than 25-35% of total kcal with less than 7% coming from saturated fat, and increasing fiber intake. According to studies, fiber decreases the rate of absorption of glucose from the small intestine, resulting in a positive effect on serum glucose levels. Guidelines enforce monitoring total grams of carbohydrates because it is an accurate predictor of glycemic response and a strategy to help achieve improved glycemic control.

A Vegetarian Diet And T2DMAccording to research, T2DM is only half as prevalent in vegetarians compared to non-vegetarians.

Evidence shows that a vegetarian diet improves carbohydrate and lipid abnormalities in diabetes.

Randomized controlled intervention studies in patients with T2DM have shown greater rates of weight loss, reduced fasting plasma glucose levels, improvements in Hb A1c values and reduced uses of diabetes medications compared with conventional diets used for the treatment of diabetes.

A Vegetarian Diet And T2DM Cont.Proposed mechanisms of interest that may help explain the beneficial effect of implementing a vegetarian diet in individuals with T2DM include:

higher intakes of fiberlower intakes of saturated fat an improved polyunsaturated and saturated fat ratiohigher intakes of non-heme ironreduced iron storeshigher intakes of plant proteins and plant sterolshigher consumptions of antioxidants.

A Vegetarian Diet And T2DMStudies have shown that increased fiber intake is associated with reductions in blood glucose, and fasting insulin in T2DM. Evidence shows that viscous fibers play a role in improving postprandial glycemia in both individuals with T2DM and individuals without T2DM.

According to a meta-analysis , selection of plant-based, low glycemic index foods was expected to allow increased consumption of carbohydrates in replacement of animal protein in the vegetarian diet, without altering the glycemic control in the postprandial period.

Evidence has revealed that there is an overall benefit in T2DM in correlation with consuming low glycemic index foods.

Therefore, the importance of slowing the rate of carbohydrate absorption is critical in improving metabolic control in patients with T2DM.

Study 1Vegetarian diet improves insulin resistance and oxidative stress markers more than conventional diet in subjects with Type 2 diabetes Kahleova H, Matoulek M, Malinska H, et al.

The study evaluated insulin resistance and oxidative stress markers in patients with type 2 diabetes in correlation with a vegetarian diet and conventional diet.

24 week randomized, open, parallel, metabolically controlled design

74 subjects with type 2 diabetesn=37 vegetarian dietn=37 conventional diet

Study 1 ParametersPatients randomly assigned to vegetarian diet group or the conventional diabetic diet group. REE Measurements were recorded by indirect calorimetry to create a calorie restriction of 500 calories per day and isocaloric diets for all subjects. All meals were provided during the study.Weekly meetings were used to encourage compliance to the prescribed diets

All measurements were recorded at baseline, 12 weeks, and 24 weeks on an outpatient basis, after 10-12 hour overnight fasting. Height, weight, waist circumference Insulin sensitivity Volume of visceral and subcutaneous fat Oxidative stress markers

Study 1 DietsThe vegetarian diet:Animal products were limited to one portion of low-fat yogurt per day.Energy breakdown ~ 60% from carbohydrates15% from protein 25% from fat.

The conventional diabetic diet:Administered according to the dietary guidelines of the diabetic and nutrition study group of the European Association for the study of diabetes. Energy breakdown:50% from carbohydrates20% from protein less than 30% from fat. Vitamin B12 was supplemented to both groups to maintain the same level of intervention.

Study 1 ResultsTrialConventionalP valueAdhereance Wk 2455%32%Weight Loss-6.2 kg-3.2 kg