Free Fatty Acid-Induced Hypertension in Obese Subjects With Type 2 Diabetes

Overview

Insulin resistance has been implicated as the central pathogenetic feature of cardiovascular risk factor cluster that includes hypertension, impaired glucose tolerance, diabetes, dyslipidemia, and hemostatic disorders. Recent evidence suggests that increased levels of free fatty acids (FFA) in obese subjects is a leading candidate in the pathogenesis of insulin resistance (1-4). In our preliminary studies on the effect of FFA on insulin secretion and action (lipotoxicity), we have observed that the infusion of Intralipid/heparin to increase FFA ~ four-fold-baseline levels for 48 hours results in a significant and reproducible raise in systolic and diastolic blood pressure (BP) in obese African American subjects with and without diabetes. The increase in blood pressure is apparent after 12 hours of infusion, reaching a peak increment of 32 mm Hg in systolic and 14 mm Hg in diastolic pressure at 24 hours. These preliminary findings indicate that, in addition to the well-known effect on insulin resistance, sustained elevation of FFA results in the development of an acute metabolic syndrome.

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Triple (Participant, Care Provider, Investigator)
  • Study Primary Completion Date: December 2009

Detailed Description

The FFA-induced hypertension constitutes a useful model with which to examine disease mechanisms and test new therapeutic interventions to correct the different disorders associated with insulin resistance and metabolic syndrome. The effect of FFA on insulin action is well established (4-6); however, the pressor effect of FFA infusion in obese subjects has not been investigated. We hypothesize that observed changes in blood pressure is the result of acute endothelial dysfunction due to increased FFA concentration; and that rosiglitazone, a PPAR gamma receptor agonist, will protect against FFA-induced elevation in blood pressure and endothelial dysfunction in obese subjects.

Interventions

  • Drug: Rosiglitazone
    • Diabetic subjects will be receive rosiglitazone for 6 weeks
  • Drug: Normal saline 0.9%
    • Normal saline 0.9% intravenous infusion at 40ml/hr for 48 hours
  • Drug: Intralipid 20%
    • Intralipid 20% at 40ml/hr intravenously for 48 hours

Arms, Groups and Cohorts

  • Active Comparator: Diabetics
    • Obese, normotensive African-Americans with diabetes received Intralipid 20% at 40ml/hr intravenously for 48 hours, then normal saline 0.9% at 40 ml/hr intravenously for 48 hours, and then randomized to rosiglitazone for six weeks followed by Intralipid 20% at 40ml/hr intravenously for 48 hours
  • Active Comparator: Non-Diabetic
    • Obese, normotensive African-Americans without diabetes received Intralipid 20% at 40ml/hr intravenously for 48 hours

Clinical Trial Outcome Measures

Primary Measures

  • Changes in Systolic Blood Pressure During Initial Intralipid Infusion
    • Time Frame: Baseline, 48 hours
    • Systolic blood pressure change from baseline during an 48-hour intralipid infusion

Secondary Measures

  • Changes in Systolic Blood Pressure During Saline Infusions
    • Time Frame: 48 hours
    • Systolic blood pressure change from baseline during an 48-hour normal saline infusion in obese diabetic subjects
  • Changes in Systolic Blood Pressure During Intralipid Infusion Post-rosiglitazone Intervention
    • Time Frame: 48 hours
    • Systolic blood pressure change from baseline during an 48-hour intralipid infusion after taking rosiglitazone for 6 weeks in obese diabetic subjects

Participating in This Clinical Trial

Inclusion Criteria

  • Males or females between the ages of 18 and 70 years.
  • Subjects must have a BMI of ≥ 30 kg/m2.
  • Subjects must have a BP < 130/80 mm Hg and no prior history of hypertension.
  • A known history of type 2 diabetes mellitus < 3 years (now 5 years).
  • Subjects must have an HbA1c of < 9%.
  • Diabetic subjects must have been receiving as their only current anti-diabetic therapy stable doses of sulfonylureas for the last 2 months.
  • Subjects must be able to understand and willing to adhere to the study protocol.

Exclusion Criteria

  • Subjects with history of hypertension (BP > 140/90 mm HG) or who have received antihypertensive drug therapy prior to the study.
  • Obese nondiabetic controls with impaired glucose tolerance (2-hour glucose between 140 – 199 mg/dl) during a 75-g OGTT.
  • Diabetic subjects who require insulin therapy or have received an insulin sensitizer agent (metformin, rosiglitazone, pioglitazone) within 3 months of entering the study (at SV1, week-2).
  • Subjects with fasting triglyceride levels > 250 mg/dL prior to the study (at SV1, week-2).
  • Clinically relevant hepatic disease (ALT 2.5x > upper limit of normal), or other significant medical or surgical illness.
  • Renal failure, as shown by a serum creatinine ≥1.5 mg/dL for males, or ≥ 1.4 mg/dL for females.
  • Mental condition rendering the subject unable to understand the nature, scope, and possible consequences of the study.
  • Female subjects are pregnant or breast feeding at time of enrollment into the study.

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • Emory University
  • Collaborator
    • GlaxoSmithKline
  • Provider of Information About this Clinical Study
    • Principal Investigator: Guillermo Umpierrez, Professor – Emory University
  • Overall Official(s)
    • Guillermo Umpierrez, MD, Principal Investigator, Emory University

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