The healthy Nordic diet for blood glucose control: a systematic review and meta-analysis of randomized controlled clinical trials
Investigations on the possible effect of the Nordic diet (ND) on the glycemic control and the risk of diabetes have led to inconsistent results. The present study tried to determine the effect of the ND on the markers of blood glucose control using a systematic review and meta-analysis of randomized controlled clinical trials (RCTs).
Predefined keywords were used to search PubMed, ISI Web of Science, Scopus and Google Scholar up to April 2019. The random effects model was used to compute the overall estimates.
In total, six RCTs with 618 participants (6–26 weeks of follow-up period) were included in the present study. The meta-analysis revealed that the ND might not have a considerable effect on fasting blood glucose levels [weighted mean difference (WMD) = −0.05 mmol/l, 95% CI − 0.13, 0.01, P = 0.112]. In contrast, the analyses showed that the ND significantly reduces serum insulin concentrations (WMD = −1.12 mU/l, 95% CI − 1.84, − 0.39, P = 0.002) and the homeostasis model assessment for insulin resistance (HOMA-IR) (WMD = − 0.34, 95% CI − 0.53, − 0.14, P = 0.001) compared to control diets. The effect on serum insulin levels was sensitive to one of the included studies. This dietary pattern did not significantly affect 2-h post-prandial blood glucose and Matsuda index.
Adherence to the ND might improve serum insulin and HOMA-IR levels; however, this effect was not confirmed for other markers of blood glucose control. Future well-designed and long-term clinical trials are highly recommended.
KeywordsNordic diet Baltic sea diet Fasting blood sugar Insulin HOMA-IR Meta-analysis
The authors’ contribution was as follows: ASA, MM, and NRJ conceived and designed the research; MM and NRJ conducted the systematic research and study selection; MM, NRJ, and AZ extracted data; ASA and MM analyzed data; AZ, MM and ASA wrote and edited the manuscript. All authors read and approved the final manuscript.
The study was funded by Nutrition and Food Security research center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran (Grant No. 5961).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest to report for the present study.
This article does not contain any studies with human participants performed by any of the authors.
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