The Effect of 4 Weeks of L-Citrulline Supplementation on Macro- and Microvascular Function in Type 2 Diabetes

The Effect of 4 Weeks of L-Citrulline Supplementation on Macro- and Microvascular Function in Type 2 Diabetes

The purpose of this study is to examine the effect of 4 weeks of Citrulline supplementation on macro- and microvascular function during acute hyperglycemia in middle-aged and older adults with type 2 diabetes.

Using a double-blind, randomized, placebo-controlled, and cross-over design, middle-aged and older adults with type 2 diabetes will be randomized to receive either CIT supplementation (6g/day) or placebo (Microcrystalline Cellulose, 6g/day) for 4 weeks.

There will be a total of 5 laboratory visits. Visit 1 (screening visit) will take approximately 1 hour and 30 minutes, visit 2 will take approximately 2 hours and 30 minutes, and visits 3-5 will be approximately 3 hours each.

Visit 1 will measure blood pressure, blood glucose and lipid levels, anthropometry, body composition, and muscle strengths. Visits 2-5 will assess vascular function and glucose control during fasted and acute hyperglycemia conditions induced by 75g of glucose ingestion.

Inclusion Criteria:

• Middle-aged and older women and men between 40-75 years old
• A physician diagnosed type 2 diabetes at least 3 months ago
• Treated with an oral hypoglycemic medication
• Body mass index < 40 kg/m2
• Systolic blood pressure < 160 mmHg
• Sedentary (defined as < 120 min/week of exercise)
• Not currently participating in exercise or dietary interventions for at least 2 months prior the present study and willing to abstain from participating in those strategies during the duration of this study.

Exclusion Criteria:

• < 40 years of age and > 65 years of age
• Use of medications and/or any supplements that may affect outcome variables (such as arginine- or citrulline-containing supplements, nitrates, and nitroglycerin)
• Body mass index ≥ 40 kg/m2
• Systolic blood pressure ≥ 160 mmHg
• Recent changes in medications within 3 months
• Current smoking any tobacco use
• Type 1 diabetes, severe cardiovascular/renal/pulmonary diseases
• More than 7 alcoholic drinks/week of consumption
• Premenopausal women with an irregular menstrual cycle (oligomenorrhea) or pregnancy