title: Unstable bodyweight and incident type 2 diabetes mellitus: A meta-analysis.
abstract: OBJECTIVE
  The present meta-analysis aimed to clarify the association of unstable bodyweight with the risk of type 2 diabetes mellitus, an association that has been controversial among longitudinal studies.
  
  
  METHODS
  An electronic literature search using EMBASE and MEDLINE was followed up to 31 August 2016. The relative risks (RRs) of type 2 diabetes mellitus in individuals with unstable bodyweight were pooled using the inverse variance method.
  
  
  RESULTS
  Eight studies were eligible for the meta-analysis. The median duration of measurements of weight change and follow-up years for ascertaining type 2 diabetes mellitus were 13.5 and 9.4 years, respectively. The pooled RR for the least vs most stable category was 1.33 (95% confidence interval 1.12-1.57). Between-study heterogeneity was statistically significant (P = 0.048). Whether type 2 diabetes mellitus was ascertained by blood testing explained 66.0% of the variance in the logarithm of RR (P = 0.02). In three studies in which blood testing was carried out, type 2 diabetes mellitus risk was not significant (RR 1.06, 95% confidence interval 0.91-1.25). Furthermore, publication bias that inflated type 2 diabetes mellitus risk was statistically detected by Egger's test (P = 0.09).
  
  
  CONCLUSIONS
  Unstable bodyweight might be modestly associated with the elevated risk of type 2 diabetes mellitus; although serious biases, such as diagnostic suspicion bias and publication bias, made it difficult to assess this association.
authors.affiliation: Department of Laboratory Medicine and Clinical Epidemiology for Prevention of Noncommunicable Diseases, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Kodama
authors.affiliation: Department of Hematology, Endocrinology and Metabolism, Niigata University Faculty of Medicine, Niigata, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Fujihara
authors.affiliation: Department of Hematology, Endocrinology and Metabolism, Niigata University Faculty of Medicine, Niigata, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Ishiguro
authors.affiliation: Department of Health and Nutrition, Faculty of Human Life Studies, University of Niigata Prefecture, Niigata, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Horikawa
authors.affiliation: Department of Hematology, Endocrinology and Metabolism, Niigata University Faculty of Medicine, Niigata, Japan.
authors.forename: Nobumasa
authors.initials: N
authors.lastname: Ohara
authors.affiliation: Department of Administrative Dietetics, Faculty of Health and Nutrition, Yamanashi Gakuin University, Yamanashi, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yachi
authors.affiliation: Department of Clinical Trial, Design & Management, Translational Research Center, Kyoto University Hospital, Kyoto, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Department of Internal Medicine, University of Tsukuba Institute of Clinical Medicine, Ibaraki, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shimano
authors.affiliation: Department of Laboratory Medicine and Clinical Epidemiology for Prevention of Noncommunicable Diseases, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Kiminori
authors.initials: K
authors.lastname: Kato
authors.affiliation: Department of Hematology, Endocrinology and Metabolism, Niigata University Faculty of Medicine, Niigata, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Hanyu
authors.affiliation: Department of Hematology, Endocrinology and Metabolism, Niigata University Faculty of Medicine, Niigata, Japan.
authors.forename: Hirohito
authors.initials: H
authors.lastname: Sone
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology*; D006801:Humans; D015430:Weight Gain; D015431:Weight Loss
keywords: Meta-analysis; Type 2 diabetes mellitus; Weight cycling