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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

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.


Condition or disease Intervention/treatment Phase
Borderline Hypokalemia Drug: K+ supplement Drug: Placebo Phase 2

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 61 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: The Effects of Potassium on Glucose Metabolism in African Americans
Study Start Date : January 2015
Actual Primary Completion Date : February 29, 2016
Actual Study Completion Date : February 29, 2016

Resource links provided by the National Library of Medicine


Arm Intervention/treatment
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
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

Drug: Placebo



Primary Outcome Measures :
  1. 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).


Secondary Outcome Measures :
  1. 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

  2. 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.

  3. 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]).



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Ages Eligible for Study:   30 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Criteria

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.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02236598


Locations
United States, North Carolina
Duke University Medical Center
Durham, North Carolina, United States, 27710
Sponsors and Collaborators
Duke University
Investigators
Principal Investigator: Ranee C Montgomery, MD Duke University

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Duke University
ClinicalTrials.gov Identifier: NCT02236598     History of Changes
Other Study ID Numbers: Pro00056374
First Posted: September 10, 2014    Key Record Dates
Results First Posted: May 23, 2017
Last Update Posted: May 23, 2017
Last Verified: April 2017

Keywords provided by Duke University:
borderline hypokalemia
glucose tolerance
insulin secretion
insulin sensitivity
fasting glucose
African American

Additional relevant MeSH terms:
Hypokalemia
Potassium Deficiency
Water-Electrolyte Imbalance
Metabolic Diseases
Deficiency Diseases
Malnutrition
Nutrition Disorders