Observational Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Diabetes. Apr 15, 2017; 8(4): 154-164
Published online Apr 15, 2017. doi: 10.4239/wjd.v8.i4.154
Effects of intermittent fasting on health markers in those with type 2 diabetes: A pilot study
Terra G Arnason, Matthew W Bowen, Kerry D Mansell
Terra G Arnason, Department of Medicine, College of Medicine, University of Saskatchewan, Saskatoon, SK S7K 5E5, Canada
Matthew W Bowen, Kerry D Mansell, Division of Pharmacy, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK S7K 5E5, Canada
Author contributions: Arnason TG and Mansell KD contributed equally to this work; Arnason TG and Mansell KD designed the research; Bowen MW performed the research, designed the analytical tools and analysed the data; Arnason TG and Mansell KD wrote the paper.
Supported by Department of Medicine, University of Saskatchewan, and the College of Pharmacy and Nutrition, University of Saskatchewan.
Institutional review board statement: The study was reviewed and approved by the University of Saskatchewan Biomedical Research Ethics Board.
Informed consent statement: All study participants provided informed written consent prior to study enrollment.
Conflict-of-interest statement: There are no conflicts of interest to report.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Kerry D Mansell, BSP, PharmD, MBA, Associate Professor, Division of Pharmacy, College of Pharmacy and Nutrition, University of Saskatchewan, 104 Clinic Place, Saskatoon, SK S7K 5E5, Canada. kerry.mansell@usask.ca
Telephone: +1-306-9665235 Fax: +1-306-9666377
Received: November 25, 2016
Peer-review started: November 26, 2016
First decision: January 16, 2017
Revised: February 11, 2017
Accepted: February 28, 2017
Article in press: March 2, 2017
Published online: April 15, 2017
Processing time: 139 Days and 17.9 Hours
Abstract
AIM

To determine the short-term biochemical effects and clinical tolerability of intermittent fasting (IF) in adults with type 2 diabetes mellitus (T2DM).

METHODS

We describe a three-phase observational study (baseline 2 wk, intervention 2 wk, follow-up 2 wk) designed to determine the clinical, biochemical, and tolerability of IF in community-dwelling volunteer adults with T2DM. Biochemical, anthropometric, and physical activity measurements (using the Yale Physical Activity Survey) were taken at the end of each phase. Participants reported morning, afternoon and evening self-monitored blood glucose (SMBG) and fasting duration on a daily basis throughout all study stages, in addition to completing a remote food photography diary three times within each study phase. Fasting blood samples were collected on the final days of each study phase.

RESULTS

At baseline, the ten participants had a confirmed diagnosis of T2DM and were all taking metformin, and on average were obese [mean body mass index (BMI) 36.90 kg/m2]. We report here that a short-term period of IF in a small group of individuals with T2DM led to significant group decreases in weight (-1.395 kg, P = 0.009), BMI (-0.517, P = 0.013), and at-target morning glucose (SMBG). Although not a study requirement, all participants preferentially chose eating hours starting in the midafternoon. There was a significant increase (P < 0.001) in daily hours fasted in the IF phase (+5.22 h), although few attained the 18-20 h fasting goal (mean 16.82 ± 1.18). The increased fasting duration improved at-goal (< 7.0 mmol/L) morning SMBG to 34.1%, from a baseline of 13.8%. Ordinal Logistic Regression models revealed a positive relationship between the increase in hours fasted and fasting glucose reaching target values (χ2 likelihood ratio = 8.36, P = 0.004) but not for afternoon or evening SMBG (all P > 0.1). Postprandial SMBGs were also improved during the IF phase, with 60.5% readings below 9.05 mmol/L, compared to 52.6% at baseline, and with less glucose variation. Neither insulin resistance (HOMA-IR), nor inflammatory markers (C-reactive protein) normalized during the IF phase. IF led to an overall spontaneous decrease in caloric intake as measured by food photography (Remote Food Photography Method). The data demonstrated discernable trends during IF for lower energy, carbohydrate, and fat intake when compared to baseline. Physical activity, collected by a standardized measurement tool (Yale Physical Activity Survey), increased during the intervention phase and subsequently decreased in the follow-up phase. IF was well tolerated in the majority of individuals with 6/10 participants stating they would continue with the IF regimen after the completion of the study, in a full or modified capacity (i.e., every other day or reduced fasting hours).

CONCLUSION

The results from this pilot study indicate that short-term daily IF may be a safe, tolerable, dietary intervention in T2DM patients that may improve key outcomes including body weight, fasting glucose and postprandial variability. These findings should be viewed as exploratory, and a larger, longer study is necessary to corroborate these findings.

Keywords: Intermittent fasting; Type 2 diabetes; Remote food photography; Self-monitored blood glucose; Homeostasis model of assessment for insulin resistence index

Core tip: Intermittent fasting (IF) involves limiting food intake into a single 4 to 8 h period, daily. We observed the tolerability, safety and health benefits of IF in 10 type 2 diabetes mellitus (T2DM) patients during a 2-wk IF intervention. Outcomes were measured after the three study phases; baseline, intervention, and follow-up. Although short, the IF phase significantly improved weight loss and fasting glucose levels, was well tolerated, and hypoglycemia was not observed. During follow-up, glucose levels reverted. This simple, outpatient-directed dietary manipulation may prove valuable in T2DM individuals with exercise intolerance, who are resistant to complex diet regimes, or are not at glycemic goals.