Walnuts and Glucose Variability

The Effect of Walnuts on Glucose Variability in Adults With Type-2 Diabetes Mellitus: a Dose-response Metabolic Feeding Study

Persons with type 2 diabetes mellitus (T2DM) have swings in their blood sugar levels that may lead to a higher risk of developing heart disease. An important part of diabetes management involves eating a diet to prevent large swings in blood sugar levels. Walnuts contain fat, protein and fiber that may reduce the swings in blood sugar. The purpose of this study is to compare the effects of a walnut-free American Diabetes Association (ADA) diet versus 2 levels of walnut-enriched ADA diets on blood sugar swings. Eighteen male and female adults with T2DM will participate in the study. Subjects will be randomized to consume an ADA diet with or without walnuts for 3 consecutive days every other week. Subjects must test their blood sugar twice daily and wear a continuous glucose monitor during the three 72-hour study periods. Subjects will be between 40 and 70 years of age and will be recruited from the surrounding community using flyers and public service announcements. Consent will take place in the Department of Nutrition at Loma Linda University by the study investigators. In total, subject participation will last 5 weeks and all meals will be provided during the 3 study periods.

Study Overview

• Status: Terminated
• Conditions: Type-2 Diabetes
• Intervention / Treatment: Dietary supplement: Full dose; Dietary supplement: Half dose; Dietary supplement: Control

• Study Type: Interventional
• Enrollment (Actual): 18
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • Loma Linda, California, United States, 92350
      • Loma Linda University, Nichol Hall

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 40 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• adults between age 40 and 70 years with type 2 diabetes
• duration of type 2 diabetes more than 6 months but less than 10 years
• HbA1c 6.0-8.0%
• BMI 25-40 kg/m2
• diet controlled or stable dose of metformin for at least 3 months
• willing to test blood glucose with personal meter twice a day during study test days

Exclusion Criteria:

• using oral hypoglycemic agents or insulin
• history of ischemic heart disease or congestive heart failure
• history of severe diabetic complication (neuropathy, renal failure, stroke)
• taking medication affecting glucose levels (i.e. corticosteroids)
• active infectious disease
• active malignancy
• pregnant or breast feeding woman
• smoker
• history of daily caffeine or alcohol intake
• known allergy to nuts
• lactose or gluten intolerance

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Full dose; full dose of walnuts (20% energy needs)	Dietary supplement: Full dose; 20% of daily energy needs supplied by walnuts
Active Comparator: Half-dose; Half dose of walnuts (10% of energy needs)	Dietary supplement: Half dose; 10% of daily energy needs supplied by walnuts
Other: Control; Walnut free meals	Dietary supplement: Control; Walnut free meals

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Within-day glucose variability	The primary objective is to evaluate the effect of two isocaloric walnut-enriched meal plans versus a walnut-free ADA meal plan on within-day glucose variability in adults with diabetes by assessing: a) the overall standard deviation (SD) around the sensor glucose calculated for each day and then averaged over the 3-day study periods; b) the mean amplitude of glycemic excursions (MAGE) over the 3-day study periods.	3 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glucose variability dose response	A secondary objective will be to test for a dose-response effect, i.e. the more walnuts (full-dose versus half-dose) the lower the glucose variability.	3 days
Dose response to between-day glycemic variability	The effect of the three isocaloric ADA meal plans (full-dose, half-dose, walnut free) on the mean of the daily differences(MODD) will be recorded as a measure of between-day glycemic variability	3 days
Glucose levels by meal	Glucose levels will be measured before and after breakfast, lunch and dinner for each of the three isocaloric ADA meal plans (full-dose, half-dose, walnut free)	3 days
Mean glucose of sensor range	The mean of the glucose for the range captured on each sensor (sensor maximal glucose level minus minimal glucose level will be recorded	3 days
Duration of hypoglycemia	The duration of hypoglycemia will be measured as hours per day for each of the three isocaloric ADA meal plans (full-dose, half-dose, walnut free)	3 days
Duration of hyperglycemia	The duration of hyperglycemia will be measured as hours per day for each of the three isocaloric ADA meal plans (full-dose, half-dose, walnut free)	3 days
Net glycemia at 2 hours	The continuous overall net glycemic action will be measured at 2 hour intervals	3 days
Net glycemia at 4 hours	The continuous overall net glycemic action will be measured at 4 hour intervals	3 days

Collaborators and Investigators

• Sponsor: Loma Linda University
• Collaborators: California Walnut Commission
• Investigators: Principal Investigator: Michelle Wien, DrPH, RD, Assistant Professor

Study record dates

Study Major Dates

• Study Start: June 1, 2013
• Primary Completion (Actual): September 1, 2013
• Study Completion (Actual): September 1, 2013

Study Registration Dates

• First Submitted: February 1, 2013
• First Submitted That Met QC Criteria: February 6, 2013
• First Posted (Estimate): February 8, 2013

Study Record Updates

• Last Update Posted (Estimate): March 18, 2014
• Last Update Submitted That Met QC Criteria: March 17, 2014
• Last Verified: March 1, 2014

More Information

Terms related to this study

• Keywords: glycemia; glucose variability; type-2 diabetes
• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Endocrine System Diseases; Diabetes Mellitus; Diabetes Mellitus, Type 2
• Other Study ID Numbers: walnuts and glucose