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The Effects of Potassium on Glucose Metabolism in African Americans

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ClinicalTrials.gov Identifier: NCT02236598
Recruitment Status : Completed
First Posted : September 10, 2014
Results First Posted : May 23, 2017
Last Update Posted : May 23, 2017
Sponsor:
Information provided by (Responsible Party):
Duke University

Tracking Information
First Submitted Date  ICMJE September 8, 2014
First Posted Date  ICMJE September 10, 2014
Results First Submitted Date  ICMJE February 14, 2017
Results First Posted Date  ICMJE May 23, 2017
Last Update Posted Date May 23, 2017
Study Start Date  ICMJE January 2015
Actual Primary Completion Date February 29, 2016   (Final data collection date for primary outcome measure)
Current Primary Outcome Measures  ICMJE
 (submitted: April 19, 2017)
Change in Glucose Tolerance as Measured by Area-under-the-curve [ Time Frame: Baseline to 3 months ]
Change in glucose tolerance, as measured by change in glucose area-under-the-curve (Area Under the Curve (AUC) - measured via the trapezoidal method) of 2 hours from the 3-hour Oral Glucose Tolerance Test (OGTT).
Original Primary Outcome Measures  ICMJE
 (submitted: September 8, 2014)
Change in Glucose Tolerance [ Time Frame: 3 months ]
Change in glucose tolerance, as measured by change in glucose area-under-the-curve (AUC) of a 3-hour oral glucose tolerance test (OGTT).
Change History Complete list of historical versions of study NCT02236598 on ClinicalTrials.gov Archive Site
Current Secondary Outcome Measures  ICMJE
 (submitted: April 19, 2017)
  • Changes in Fasting, 1-hour, and 2-hour Post-challenge Glucose Levels in mg/dL [ Time Frame: Baseline to 3 months ]
    Changes in fasting, 1-hour, and 2-hour post-challenge glucose levels in mg/dL
  • Changes in Insulin Secretion as Measured by 2-hour Insulin Area-under-the-curve (AUC) [ Time Frame: Baseline to 3 months ]
    Changes in Insulin Secretion as measured by 2-hour insulin area-under-the-curve (AUC - measured via the trapezoidal method) of 2 hours from the 3-hour OGTT.
  • Changes in Insulin Sensitivity [ Time Frame: Baseline to 3 months ]
    Matsuda Insulin Sensitivity Index was calculated as: 10,000 / square root of [fasting glucose x fasting insulin x mean glucose x mean insulin during Oral Glucose Tolerance Test]).
Original Secondary Outcome Measures  ICMJE
 (submitted: September 8, 2014)
  • Changes in fasting, 1-hour, and 2-hour post-challenge glucose levels [ Time Frame: 3 months ]
    Changes in fasting, 1-hour, and 2-hour post-challenge glucose levels
  • Changes in Insulin Secretion [ Time Frame: 3 months ]
    Changes in insulin secretion as measured by OGTT Minimal Model Analyses Method of Cobelli et al, Diabetes 63: 1203-1213, 2014, using plasma c-peptide & insulin values obtained at 0, 10, 20, 30, 60, 90, 120, 180 minutes after a standard 75 gram oral glucose challenge.
  • Changes in Insulin Sensitivity [ Time Frame: 3 months ]
    Changes in insulin sensitivity by Oral glucose tolerance test Minimal Model analyses of Cobelli et al., Diabetes 63: 1203-1213, 2014
Current Other Pre-specified Outcome Measures Not Provided
Original Other Pre-specified Outcome Measures Not Provided
 
Descriptive Information
Brief Title  ICMJE The Effects of Potassium on Glucose Metabolism in African Americans
Official Title  ICMJE The Effects of Potassium on Glucose Metabolism in African Americans
Brief Summary

African Americans suffer a disproportionately high risk of diabetes compared to other Americans. Reasons for race disparities in diabetes incidence are not completely understood. Although a difference in prevalence of obesity does explain a significant portion of the racial disparity in diabetes risk, it does not explain all of this disparity. Strategies to control the diabetes epidemic and reduce its racial disparity often overlook preventive measures. Currently, the most powerful known strategy for preventing diabetes is weight loss in the overweight/obese. However, because weight loss is often difficult to achieve and maintain, other opportunities to prevent diabetes should be identified, particularly in African Americans. Among potential novel opportunities is correction of low or low-normal potassium levels (hypokalemia). In secondary analyses, we have found low-normal potassium (K) to be a novel risk factor for diabetes; and we have found that this association between low-K and diabetes risk may be stronger in African Americans compared to whites. Therefore, a previously unrecognized alternative or adjunct strategy for preventing diabetes, particularly in African Americans, may involve correction of low or low-normal K levels (hypokalemia). Large-scale, adequately-powered, randomized controlled trials are needed to establish the effectiveness of this approach. However, prior to those trials, the pathophysiology of the association between low K and poor glucose metabolism must be understood. This pilot clinical trial will begin to determine the effect of K supplementation on measures of glucose metabolism in African Americans.

In this pilot clinical trial, 30 African Americans with prediabetes and a low-normal serum K [<4.0 milliequivalent/Liter (Eq/L)] will be randomized to K-supplements, 20mEq (2-10mEq tablets) twice daily or a matching placebo capsules twice daily. Prior to randomization, baseline measures will be taken including measures of glucose metabolism with a 3-hour oral glucose tolerance test (OGTT), baseline chemistries and a baseline 24-hour urinary potassium measurement. Patients will take the intervention daily and will undergo repeat testing of all of these measures at the end of a 3 month period. The primary endpoint will be change in glucose tolerance, as measured by change in glucose area-under-the-curve (AUC) of a 3-hour oral glucose tolerance test (OGTT). Secondary endpoints will include changes in fasting, 1-hour, and 2-hour post-challenge glucose levels, as well as measurements of insulin secretion and insulin sensitivity as measures by the oral glucose minimal model method.(1) The baseline data from this trial will allow us to quantify abnormalities in glucose metabolism in African Americans with prediabetes/early diabetes and low-normal serum K. The post-intervention data will provide estimates of the impact of K-supplements compared to no supplements on these abnormalities. Data derived from the pilot study will be used in the design of a larger scale, adequately powered clinical trial. This trial will also help to assess the feasibility of recruiting this target population.

With this pilot trial, we will begin to determine whether or not K-supplements, an inexpensive, well-tolerated, and simple intervention, could help to reduce diabetes risk among African Americans.

Detailed Description Not Provided
Study Type  ICMJE Interventional
Study Phase  ICMJE Phase 2
Study Design  ICMJE Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Condition  ICMJE Borderline Hypokalemia
Intervention  ICMJE
  • Drug: K+ supplement
  • Drug: Placebo
Study Arms  ICMJE
  • Experimental: K+ supplementation
    K-supplement- Klor-Con® M10 is an immediately dispersing extended-release oral dosage form of potassium chloride containing 750 mg of microencapsulated potassium chloride, United States Pharmacopeia (USP) equivalent to 10 milliequivalent (mEq) of potassium in a tablet. Participants will be instructed to take two 10 mEq tablets twice daily in a blinded encapsulated form, for 3 months
    Intervention: Drug: K+ supplement
  • Experimental: Placebo

    Placebo - An inert powdered placebo will be identically encapsulated as the Klor-Con intervention tablets to maintain blinding. Participants will be instructed to take two tablets twice daily in a blinded encapsulated form, for 3 months

    Subjects will be instructed to take the pills

    Intervention: Drug: Placebo
Publications * Chatterjee R, Slentz C, Davenport CA, Johnson J, Lin PH, Muehlbauer M, D'Alessio D, Svetkey LP, Edelman D. Effects of potassium supplements on glucose metabolism in African Americans with prediabetes: a pilot trial. Am J Clin Nutr. 2017 Dec;106(6):1431-1438. doi: 10.3945/ajcn.117.161570. Epub 2017 Nov 1.

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Recruitment Information
Recruitment Status  ICMJE Completed
Actual Enrollment  ICMJE
 (submitted: February 11, 2016)
61
Original Estimated Enrollment  ICMJE
 (submitted: September 8, 2014)
30
Actual Study Completion Date  ICMJE February 29, 2016
Actual Primary Completion Date February 29, 2016   (Final data collection date for primary outcome measure)
Eligibility Criteria  ICMJE

Inclusion Criteria:

To be eligible for inclusion in the study the following enrollment criteria must be met:

  1. Participants must be 30 years of age or older.
  2. They must have a diagnosis of prediabetes defined as a hemoglobin A1c between 5.7-6.5% measured at the initial screening visit.
  3. They must have a serum K+ of 3.3-4.0 mEq/L on 2 occasions, within a 18 month period, including at initial screening visit. If subject is just outside range for inclusion, PI may offer the subject the option to repeat their screening serum K+ measurement.
  4. The participant must be willing and capable of providing written informed consent.
  5. The participant must be available for follow-up and must at minimum have telephone access.
  6. Participants must be able to read/understand English.

Exclusion Criteria:

  • Participants must not have any of the following:

    1. Participants must not have evidence of chronic kidney disease with an estimated Glomerular Filtration Rate (eGFR) < 60ml/min. All patients will be screened for eGFR at the enrollment visit.
    2. Participants must not have evidence of diabetes mellitus requiring treatment with medications prior to screening visit. The cannot have a random or post-challenge glucose ≥ 200mg/dl (from prior labs), A1c level ≥ 6.5% (from prior labs), prior physician diagnosis, or use of anti-diabetic medications. If participants have glucose levels in the diabetic range at screening visit, they will be eligible to continue in study as long as glucose levels are not > 200 mg/dl.
    3. Participants must not have a history of endoscopy-verified peptic ulcer disease with past history of either gastric or duodenal ulcer.
    4. Participants must not have evidence of cardiac arrhythmias, unstable angina or cardiac event within 6 months, congestive heart failure, or other conditions that might impact follow-up, based on the discretion of the principal investigator.
    5. Participants must not be pregnant or intend to get pregnant during the study period. The study intervention is safe for pregnant women, so serum pregnancy screening is not indicated; however, pregnant women are excluded because pregnancy affects glucose homeostasis, which will bias primary outcome measurement and damage scientific validity of the study.
Sex/Gender  ICMJE
Sexes Eligible for Study: All
Ages  ICMJE 30 Years and older   (Adult, Older Adult)
Accepts Healthy Volunteers  ICMJE No
Contacts  ICMJE Contact information is only displayed when the study is recruiting subjects
Listed Location Countries  ICMJE United States
Removed Location Countries  
 
Administrative Information
NCT Number  ICMJE NCT02236598
Other Study ID Numbers  ICMJE Pro00056374
Has Data Monitoring Committee No
U.S. FDA-regulated Product Not Provided
IPD Sharing Statement  ICMJE Not Provided
Responsible Party Duke University
Study Sponsor  ICMJE Duke University
Collaborators  ICMJE Not Provided
Investigators  ICMJE
Principal Investigator: Ranee C Montgomery, MD Duke University
PRS Account Duke University
Verification Date April 2017

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP