Effects of potassium supplements on glucose metabolism in African Americans with prediabetes: a pilot trial [Vitamins, minerals, and phytochemicals]

  1. Ranee Chatterjee1,
  2. Cris Slentz1,3,
  3. Clemontina A Davenport2,
  4. Johanna Johnson1,3,
  5. Pao-Hwa Lin1,
  6. Michael Muehlbauer1,3,
  7. David D’Alessio1,3,
  8. Laura P Svetkey1, and
  9. David Edelman1
  1. 1Departments of Medicine and
  2. 2Biostatistics and Bioinformatics and
  3. 3Duke Molecular Physiology Institute, Duke University, Durham, NC
  1. Address correspondence to RC (e-mail: ranee.chatterjee{at}duke.edu).
  • This material was presented in abstract form as a poster presentation at the American Diabetes Association’s 77th Scientific
    Sessions, San Diego, CA, 12 June 2017.

  • Supported in part by the National Institute of Diabetes, Digestive, and Kidney Diseases of the NIH under award P30DK096493.
    RC and this trial were also funded by NIH/Duke Clinical and Translational Science award KL2TR001115-02. CAD was funded by
    Duke Clinical and Translational Science award/National Center for Advancing Translational Sciences award UL1TR001117.

  • Supplemental Tables 1 and 2 are available from the “Online Supporting Material” link in the online posting of the article
    and from the same link in the online table of contents at http://ajcn.nutrition.org.


Background: Low potassium has been identified both as a risk factor for type 2 diabetes and as a mediator of the racial disparity in
diabetes risk. Low potassium could be a potentially modifiable risk factor, particularly for African Americans.

Objective: We sought to determine the effects of potassium chloride (KCl) supplements, at a commonly prescribed dose, on measures of
potassium and glucose metabolism.

Design: Among African-American adults with prediabetes, we conducted a double-blinded pilot randomized controlled trial that compared
the effects of 40 mEq K/d as KCl supplements with a matching placebo, taken for 3 mo, on measures of potassium and glucose
metabolism, with measures collected from frequently sampled oral-glucose-tolerance tests (OGTTs).

Results: Twenty-seven of 29 recruited participants completed the trial. Participants had high adherence to the study medication (92%
by pill count). Participants in both groups gained weight, with an overall mean ± SD weight gain of 1.24 ± 2.03 kg. In comparison
with participants who received placebo, urine potassium but not serum potassium increased significantly among participants
randomly assigned to receive KCl (P = 0.005 and 0.258, respectively). At the end of the study, participants taking KCl had stable or improved fasting glucose,
with a mean ± SD change in fasting glucose of −1.1 ± 8.4 mg/dL compared with an increase of 6.1 ± 7.6 mg/dL in those who received
placebo (P = 0.03 for comparison between arms). There were no significant differences in glucose or insulin measures during the OGTT
between the 2 groups, but there was a trend for improved insulin sensitivity in potassium-treated participants.

Conclusions: In this pilot trial, KCl at a dose of 40 mEq/d did not increase serum potassium significantly. However, despite weight gain,
KCl prevented worsening of fasting glucose. Further studies in larger sample sizes, as well as with interventions to increase
serum potassium more than was achieved with our intervention, are indicated to definitively test this potentially safe and
inexpensive approach to reducing diabetes risk. This trial was registered at clinicaltrials.gov as NCT02236598.



  • Abbreviations used: HbA1c, glycated hemoglobin; KCl, potassium chloride; OGTT, oral-glucose-tolerance test.

  • Received May 30, 2017.
  • Accepted October 10, 2017.

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