Lifestyle Control of Postprandial Hyperglycemia

Low-carbohydrate Diet, With or Without Exercise, for Improving Postprandial Glucose Control and Vascular Function in Type 2 Diabetes and Prediabetes.

Large spikes in blood glucose experienced after meals in people with type 2 diabetes are known to damage blood vessels. Low carbohydrate high fat diets and exercise can improve blood glucose control in people with type 2 diabetes but it is unclear how these two strategies interact to affect blood vessel function and inflammation. We will examine how following a short-term low carbohydrate high fat diet (4 days) with or without post-meal walking impacts markers of blood vessel function and inflammation. We will also examine how a single low carbohydrate high fat meal, with or without post-meal walking, impacts blood glucose control and blood vessel function. Findings will help determine the best lifestyle approach for improving cardiovascular health in type 2 diabetes.

Participants will engage in 4 days of high-carbohydrate low fat diet as recommended by the Canadian Diabetes Association. The macronutrients content will go as follow: 55% carbohydrate, 25% protein and 20% fat. Breakfast, lunch and dinner will be provided to the participants as part of an isoenergetic diet. Between interventions there will be at least a one-week washout, where participants are encouraged to return to their baseline dietary habits.

Participants will engage in 4 days of low-carbohydrate high-fat diet. The macronutrients content will go as follow: 10% carbohydrate, 25% protein and 65% fat. Breakfast, lunch and dinner will be provided to the participants as part of an isoenergetic diet. Between interventions there will be at least a one-week washout, where participants are encouraged to return to their baseline dietary habits.

Participants will follow the same diet as in the low-carbohydrate diet arm but also perform 15 minutes of walking beginning ~15 minutes after breakfast, lunch and dinner. Approximately 70 kcal (individualized) will be added to main meals to account for exercise energy expenditure. Between interventions there will be at least a one-week washout, where participants are encouraged to return to their baseline dietary habits.

Difference in glycemic control assessed by continuous glucose monitoring in low-carbohydrate, low-carbohydrate plus post-meal walking, and high-carbohydrate low-fat arm.

Change from baseline in toll-like receptors 2 and 4 expression on white blood cells after 4 days of intervention.

Change from baseline in flow-mediated dilation after single breakfast meal on day 1 of the intervention

Inclusion Criteria: Diagnosed with type 2 diabetes (at least 6 months ago) Aged 40-75 Engaging in 2 or less moderate-to-vigorous exercise bouts per week in the last 3 months Ability to understand and communicate in English to interact with the personal trainer Exclusion Criteria: Diagnosed coronary artery disease Any contraindications to exercise (e.g., musculoskeletal injury) Prior history of cardio- or cerebrovascular disease or myocardial infarction Hypertension that is not controlled by medication (systolic blood pressure (BP) >160 mmHg and/or diastolic BP >99 mmHg) Change in diabetes medications in the previous 6 months Diagnosed with peripheral neuropathy Taking exogenous insulin