Effects of White Potato Consumption on Measures of Cardiometabolic Health in Individuals With Type 2 Diabetes Mellitus

Overview

The investigators are examining the effects of potato consumption on indices of glycemic control and cardiovascular health in overweight and obese individuals with type two diabetes mellitus (T2D) to provide feasible and effective dietary ways for individuals to enhance their quality of life. The overall objective of this crossover study is to collect data regarding the effects of potato consumption on indices of glycemic control and cardiovascular health among overweight and obese individuals with T2D. The central hypothesis of this crossover study is that the daily consumption of 100 g white potato for 12 weeks will contribute to improvements in glycemic control, reductions in inflammation, and improvements in blood lipids and vascular function in overweight and obese individuals with T2D compared to a macronutrient-matched refined grain (75 g cooked long-grain white rice) for 12 weeks (with a 2 week washout period between interventions). Specific Aim) The assessment of blood glucose control, vascular function, body composition and overall cardiovascular risk after consumption of potatoes (100g/d for 12 weeks) in individuals with T2D compared to a calorie matched refined grain at the initial baseline visit as well as the 6-, and 12-week study visits (for each 12-week intervention period). This aim will assess changed in blood glucose, insulin, HbA1c, HOMA-IR, and HOMA-β as well as the following: 1. blood pressure (BP) 2. markers of endothelial function \[flow-mediated dilation (FMD), pulse wave velocity (PWV), and endothelin-1 (ET-1)\] 3. markers of inflammation (C-reactive protein) 4. body composition via bioelectrical impedance (BIA), lean mass and fat mass assessment 5. lipid profiles, consisting of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and oxidized LDL (Ox-LDL). Atherogenic risk ratios (TC/HDL-C, LDL-C/HDL-C, HDL-C/LDL-C) will also be assessed 6. anthropometrics \[weight, height, waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WC/HC)\]

A total of 50 men and postmenopausal women between the ages of 45 and 80 who have T2D will be recruited for this study. Participants with T2D will be recruited from Tallahassee, FL and surrounding areas through campus and community advertisements through flyers, newspaper articles, and public events. After an initial telephone screening, all participants will be requested to report to the clinical area of the Sandels building at FSU (study site) for their first on-site visit (and all visits if the participant qualifies). On the first visit (screening), the potential participants will be provided with verbal and written explanation of the project and will have any questions regarding the study answered by trained research personnel during the informed consent process. Then the individual will be asked to sign an informed consent form, followed by a medical history questionnaire to confirm their diabetic state, and measurements of their fasting blood glucose levels and HbA1c will also be done to assess any changes that may occur throughout the study. Anthropometrics will be measured and questions on medical history and medication use will be asked during the screening visit to confirm eligibility. Randomization of participants in the potato or the calorie-matched refined grain group will be done after the screening visit and following completion of a Seven-Day Food Frequency Questionnaire (FFQ), which will indicate if individuals frequently consume potatoes. If participants are considered "non-frequent" white potato consumers (\<2 servings per week), they will be included in this study and asked to come for following visits, additionally during this visit participants will be familiarized with vascular assessments prior to their baseline appointment. On the second (baseline) visit participants will be randomly assigned to one of two groups: 1) 100 g cooked white potato or 2) 75 g calorie-matched cooked refined grain (cooked long-grain white rice) daily for 12 weeks following a 2-week washout period prior to the other intervention group (a total of 26 weeks upon completion of the study). Study foods will be prepared at the Florida State University Metabolic Kitchen and Diet Assessment Lab following SafeStaff Foodhandler Training, an approved Florida foodhandler program, protocols for preparation, storage and handling. At the baseline visit participants will be asked to come fasted; BP and vascular function will be measured followed by blood draw, anthropometrics, body composition (via BIA), and a physical activity questionnaire will be administered. Participants will be provided with their assigned dietary regimen and will receive instructions on how to fill out daily diaries for their dietary regimen and will be given three-day food records to bring back for their subsequent visits to assess typical intake throughout the study. BP, vascular function, blood draw, and anthropometric, body composition, diet, and physical activity assessments will be repeated at 6-, and 12-week visits for both intervention periods with a 2-week washout between each intervention period (for a total of 5 study visits). After the 2-week washout period, participants will be asked to come to the study site, to receive the other intervention group and be given instruction on their new dietary regimen. Participants will be asked to come to the study site on a bi-weekly basis to pick up potato and white rice regimen, which can be stored in the freezer/refrigerator prior to consumption. Additionally, participants will be given portioned cooked rice to take home with them for the long-grain white rice regimen. All cardiovascular measurements will be performed between 7:00-10:00 A.M., in a quiet temperature-controlled room after an overnight fast and 12 hours after the abstinence of caffeine and/or 24 hours after the last bout of moderate to heavy physical activity.