Does Class of Dietary Fat Affect Insulin Resistance?

Insulin Resistance Clinical Trial

Official title:

Insulin Resistance and Dietary Fat

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01541592
• Other study ID #: 11-000179
• Status: Completed
• Phase: N/A
• First received: February 21, 2012
• Last updated: November 24, 2014
• Start date: March 2012
• Est. completion date: February 2014

Study information

• Verified date: November 2014
• Source: Mayo Clinic
• Contact: n/a
• Is FDA regulated: No
• Health authority: United States: Institutional Review Board
• Study type: Interventional

Clinical Trial Summary

It has been shown that intravenous fatty acids given to normal volunteers in the form of heparin and lipid emulsions will cause insulin resistance in a matter of a few hours. It is not known if this same phenomenon can be demonstrated with oral fat. The investigators are specifically interested in whether or not there are differences in the induction of insulin resistance between the 3 main classes of fatty acids (saturated, monounsaturated and polyunsaturated).

The investigators also plan to evaluate endothelial dysfunction and blood pressure; both of which frequently accompany insulin resistance.

Description:

Type 2 Diabetes and cardiovascular disease are closely linked. A common abnormality in both conditions is insulin resistance. The primary cause of insulin resistance in not known. A significant question is what dietary components contribute to the development of insulin resistance. Based on epidemiologic data, it seems that the type of dietary fat is a significant contributor to the development of insulin resistance. However, some researchers argue that the main determinant is total amount of fat, not the composition.

This study is intended to determine if the main types of fat (saturated, monounsaturated and polyunsaturated) ingested over a short time can cause insulin resistance in lean, healthy people. It has been demonstrated that 6 hours of intravenous fat infused into lean, healthy subjects can result in insulin resistance, as well as blood pressure elevation and endothelial dysfunction. Whether this is so with oral fat is not known. The question is important because there is debate about whether the type of fat is as important as the quantity of fat in a person's daily diet. Settling this debate will enhance the ability of health care personnel to determine the optimal dietary recommendations.

This study will make use of a high fat diet consisting of vegetable oils high in the 3 main fatty acids in plasma (palmitate, oleate and linoleate). Because large fat loads can cause intestinal discomfort, a feeding tube will be used to bypass the stomach. The 3 oils will be assigned randomly following a base line study with saline 2 weeks prior to the intervention. Our primary endpoint is insulin resistance, which will be measured by a euglycemic, hyperinsulinemic clamp. Secondary measures will include changes in blood pressure and in vascular reactivity as measured by ultrasound after brief occlusion of a forearm vessel. The changes will be compared to baseline and to the other 2 groups.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 24
• Est. completion date: February 2014
• Est. primary completion date: February 2014
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 18 Years to 40 Years

Eligibility

Inclusion Criteria:

• Lean,healthy adults 18 - 40

• No chronic medications (birth control pills allowed)

• Weight stable

• Normal fasting labs performed at screening

• Body mass index = 25 kg/M^2 .

Exclusion Criteria:

• Insulin dependent diabetes

• Thyroid disease

• History of diabetes or heart disease

• History of type 2 diabetes in parent or sibling

Study Design

Allocation: Randomized, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Basic Science

Related Conditions & MeSH terms

• Insulin Resistance

Intervention

Other:
• Dietary fat
On the study day, each participant will receive 100 grams of a randomly assigned fat via a nasoduodenal tube. The oil will be infused at a rate of ~1 tablespoon per hour so that the total infusion time will be 6 hours.

Locations

Country	Name	City	State
United States	Mayo Clinic in Rochester	Rochester	Minnesota

Sponsors (1)

Lead Sponsor	Collaborator
Mayo Clinic

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Change in Insulin Sensitivity from Baseline at Two Weeks	Insulin sensitivity will be measured twice (once at baseline following a nasoduodenal infusion of saline for 6 hours; two weeks later following a nasoduodenal infusion of a vegetable oil high in one of 3 fatty acids for 6 hours) using a euglycemic, hyperinsulinemic clamp as described by R. DeFronzo. The actual measurement is expressed as a glucose infusion rate.	Average of 2 weeks.	No
Secondary	Change in Endothelial Function from Baseline at Two Weeks	Endothelial function will be measured by measuring the dilation of the brachial artery in the elbow following occlusion by a blood pressure cuff, which is then released. The actual measurement involves use of ultrasound by an investigator experienced with this technique.	Average of two weeks	No
Secondary	Change in Systolic Blood Pressure at Two Weeks	Blood pressure will be measured using a standard automated blood pressure cuff. The measurements will be taken several times during each study day.	Average of two weeks	No