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Table 1 Characteristics of the prospective studies (n = 11) regarding the associations between iron intake or body iron stores and the risk of type 2 diabetes mellitus (T2DM)

From: Dietary iron intake, body iron stores, and the risk of type 2 diabetes: a systematic review and meta-analysis

Author, year [reference number] Country Study name Sample sizea Age, years Women, % Follow-up, years Exposure assessment Ascertainment of T2DM
Iron intakes and T2DM (n = 5)      
Jiang et al, 2004 [20] USA HPFS 1168/38,394 40 to 75 0 12 FFQ (validated) Symptoms plus fasting glucose, OGTT, or use of anti-diabetic medication
Lee et al, 2004 [24] USA IWHS 1921/35,698 55 to 69 100 11 FFQ (validated) Self-report
Song et al, 2004 [23] USA WHS 1558/37,309 ≥ 45 100 8.8 FFQ (validated) Self-report
Rajpathak et al, 2006 [21] USA NHS 4599/85,031 34 to 59 100 20 FFQ (validated) Symptoms plus fasting glucose, OGTT, or use of anti-diabetic medication
Shi et al, 2010 [30] China JIN 23/1,056 ≥ 20 57.9 5 3-day weighed food records Fasting glucose
Body iron stores and T2DM (n = 6)      
Salonen et al, 1998 [9] Finland KIHD 41/82 42 to 60 0 4 sTfR (EIA) ferritin (RIA) Fasting glucose, OGTT, clinical diagnosis of diabetes or use of anti-diabetic treatment
Jiang et al, 2004 [10] USA NHS 698/716 56.5/56.4 100 10 sTfR (ITA); ferritin (ITA) Symptoms plus fasting glucose, or use of anti-diabetic medication
Forouhi et al, 2007 [11] UK EPIC-
Norfolk
360/758 62.4/62.1 42.0 5.1 Ferritin (FIA) Self-report, HbA1c
Jehn et al, 2007 [15] USA ARIC 599/690 53.5/52.8 60.4 7.9 Ferritin (ITA) Fasting or non-fasting glucose, anti-diabetic medication use, self-report
Le et al, 2009 [16] USA ACLS 220/5,292 NA 32.0 4.3-4.7 Ferritin (no details of test available) Fasting glucose, hypoglycemic medication, or ever-diagnosed T2DM
Rajpathak et al, 2009 [17] USA DPP 280/280 50.4/50.2 63.6 2.8 Ferritin (ITA) OGTT, fasting glucose
  1. Abbreviations: ACLS, Aerobics Center Longitudinal Study; ARIC, Atherosclerosis Risk in Communities; DPP, Diabetes Prevention Program; EIA, enzyme immunoassay; EPIC, European Prospective Investigation into Cancer and Nutrition; FFQ, food frequency questionnaire; FIA, fluoroimmunoassay; HbA1c, glycated hemoglobin; HPFS, Health Professionals' Follow-up Study; ITA, immunoturbidimetric assay; IWHS, Iowa Women's Health Study; JIN, Jiangsu Nutrition Study; KIHD, Kuopio Ischemic Heart Disease Risk Factor Study; NHS, Nurses' Health Study; OGTT, oral glucose tolerance test; sTfR, soluble transferrin receptor; WHS, Women's Health Study.
  2. a Sample sizes were incident cases/participants for iron intake and T2DM, and cases/controls for body iron stores and T2DM.