Diabetes Metab J.  2019 Aug;43(4):422-431. 10.4093/dmj.2018.0090.

Additional Effect of Dietary Fiber in Patients with Type 2 Diabetes Mellitus Using Metformin and Sulfonylurea: An Open-Label, Pilot Trial

  • 1Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. leemk@skku.edu
  • 2Department of Environmental Health Sciences, Graduate School of Public Health, Seoul National University, Seoul, Korea.
  • 3Department of Endocrinology and Metabolism, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, Korea.
  • 4Division of Endocrinology and Metabolism, Department of Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.


Metformin, sulfonylurea, and dietary fiber are known to affect gut microbiota in patients with type 2 diabetes mellitus (T2DM). This open and single-arm pilot trial investigated the effects of the additional use of fiber on glycemic parameters, insulin, incretins, and microbiota in patients with T2DM who had been treated with metformin and sulfonylurea.
Participants took fiber for 4 weeks and stopped for the next 4 weeks. Glycemic parameters, insulin, incretins during mixed-meal tolerance test (MMTT), lipopolysaccharide (LPS) level, and fecal microbiota were analyzed at weeks 0, 4, and 8. The first tertile of difference in glucose area under the curve during MMTT between weeks 0 and 4 was defined as "˜responders' and the third as "˜nonresponders,' respectively.
In all 10 participants, the peak incretin levels during MMTT were higher and LPS were lower at week 4 as compared with at baseline. While the insulin sensitivity of the "˜responders' increased at week 4, that of the "˜nonresponders' showed opposite results. However, the results were not statistically significant. In all participants, metabolically unfavorable microbiota decreased at week 4 and were restored at week 8. At baseline, metabolically hostile bacteria were more abundant in the "˜nonresponders.' In "˜responders,' Roseburia intestinalis increased at week 4.
While dietary fiber did not induce additional changes in glycemic parameters, it showed a trend of improvement in insulin sensitivity in "˜responders.' Even if patients are already receiving diabetes treatment, the additional administration of fiber can lead to additional benefits in the treatment of diabetes.


Diabetes mellitus, type 2; Dietary fiber; Metformin; Microbiota; Sulfonylurea compounds
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