Lifestyle Control of Postprandial Hyperglycemia

Study Overview
=================
Brief Summary
-----------------
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.

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

Conditions
-----------------
Type 2 Diabetes

Intervention / Treatment
-----------------
* Behavioral: High-carbohydrate diet
* Behavioral: Low-carbohydrate diet
* Behavioral: Low-carbohydrate diet with post-meal walking


Participation Criteria
=================
Eligibility Criteria
-----------------
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

Ages Eligible for Study
-----------------
Minimum Age: 40 Years
Maximum Age: 75 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: High-carbohydrate diet<br> | Behavioral: High-carbohydrate diet<br>* 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.<br>|
| Experimental: Low-carbohydrate diet<br> | Behavioral: Low-carbohydrate diet<br>* 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.<br>|
| Experimental: Low-carbohydrate diet with post-meal walking<br> | Behavioral: Low-carbohydrate diet<br>* 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.<br>Behavioral: Low-carbohydrate diet with post-meal walking<br>* 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.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in glycemic control assessed by continuous glucose monitoring in low-carbohydrate, low-carbohydrate plus post-meal walking, and high-carbohydrate low-fat arm. |  | 4-day average glucose levels assessed in each arm. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in circulating inflammatory cytokines after 4 days of intervention. |  | Fasting measurements taken on day 1 and day 5. | 
| Change from baseline in toll-like receptors 2 and 4 expression on white blood cells after 4 days of intervention. |  | Fasting measurements taken on day 1 and day 5. | 
| Change from baseline in flow mediated dilation of brachial artery after 4 days of intervention. |  | Fasting measurements taken on day 1 and day 5. |