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Table 1 Description of the included studies

From: Effects of zinc supplementation on diabetes mellitus: a systematic review and meta-analysis

Authors (reference), year, Country Study design Study description Parameters studies Formulation and Dose Other tested substances Significant outcomes
Afkhami-Ardekani et al., [19] 2008, Iran R, DB, P; T2DM (n=40); age 52.7 8.6year; 2 groups; 612weeks; BMI; SBP; DBP; FBG; 2-h PPBS; HbA1c; TG; TC; HDL-c; LDL-c; Urea; Creatinine; ALT; AST ZnSO4; 660mg/day# None Reduction in TG, TC, LDL and HbA1C
Al-Maroof et al., [20] 2006, Iraq R, B, P; T2DM (n=86); age 54.6 9.2year; 2 groups; 3months HbA1c; FBG ZnSO4; 30mg/day* None Reduction in HbA1C
Anderson et al., [27] 2001, Tunisia R, DB, P; T2DM (n=110); age 57.9 6.2year; 4 groups; 6months Plasma and Urinary Zinc; Antioxidant effects Zn gluconate; 30mg/day# Chromium Positive antioxidant effect
Blostein-Fujii et al., [38] 1997, USA R, B, P; T2DM (n=60); age 60.0 12.0year; 2 groups; 3weeks Plasma Zinc; 5-nucleotidase; lipoprotein oxidation; IGF-1 30mg/day# None Raised IGF-1 (only if low at initiation)
De Sena et al., [39] 2005, Brazil Casecontrol; T1DM (n=37); age 4.1 16.5year; 2 groups; 4months FBG; HbA1c; Urine sugar; Plasma and red cell Zn 7.5-15mg/day* None Increased erythrocyte Zinc concentration
Farvid et al., [28] 2011, Iran R, DB, P; T2DM (n=67); age 52.5 8.2year; 3 groups; 4months Plasma Zinc; FBG; HbA1c; Fructosamine; Antioxidant effects; Neuropathy symptoms; Nerve conduction; Peripheral blood flow ZnSO4; 20mg/day* Mg2+; Vitamin B1,B2, B6,B12, C,E; Folate Reduced severity of neuropathy symptoms in patients with mild-moderate neuropathy
Farvid et al., [29] 2005, Iran R, DB, P; T2DM (n=69); age 50.0 9.0year; 4 groups; 3months Plasma and Urinary Zinc; SBP; DBP; MAP; FBG; HbA1c; TC; TG; HDL-c; LDL-c; Apo-A1; Apo B; Fructosamine; Urinary Microalbumin and protein ZnSO4; 30mg/day* Mg2+; Vitamin C,E Lowered urinary albumin excretion
Farvid et al., [30] 2004a, Iran R, DB, P; T2DM (n=69); age 50.3 8.2year; 4 groups; 3months Plasma and Urinary Zinc; SBP; DBP; MAP ZnSO4; 30mg/day* Mg2+; Vitamin C,E Combination of vitamins and minerals decreases blood pressure
Farvid et al., [31] 2004b, Iran R, DB, P; T2DM (n=69); age 50.3 8.2year; 4 groups; 3months Plasma and Urinary Zinc; TC; HDL-c; LDL-c; TG; Apo-A1; Apo B ZnSO4; 30mg/day* Mg2+; Vitamin C,E co-supplementation of Mg, Zn, Vitamins C and E, increases HDL and Apo-A1
Faure et al., [17] 1995, France Casecontrol; T1DM (n=18); age 32.2 8.1year; 2 groups; 3months Plasma Zinc; Antioxidant effects Zn gluconate; 30mg/day* None Reduced lipid peroxidation
Garcia-Medina et al., [32] 2011, Spain R; P; T2DM (n=97); age 54.8 11.6year; 2 groups; 60months Antioxidant effects; Visual acuity; Slit-lamp examination; IOP; Fundoscopy 27mg/day* Cu2+, Mn2+, Se2+, Vitamin C, E, Niacin Retardation of retinopathy progression; improved antioxidant status
Gunasekara et al., [33] 2011, Sri Lanka R, B, P; T2DM (n=96); age 53.4 7.2year; 3 groups; 4months FBG; 2-h PPBS; HbA1c; Creatinine; Insulin; Plasma and Urinary Zinc; TC; TG; HDL-c; LDL-c ZnSO4; 22mg/day* Mg2+, Cu2+, Se2+, Multivitamin Reduced HbA1C, FBG, 2-h PPBS, TC and TC/HDL ration.
Gupta et al., [40] 1998, India R, DB, P; T2DM (n=50); age 49.9 11.0year; 3 groups; 6weeks Plasma Zinc; FBG; 2-h PPBS; Nerve conduction tests ZnSO4; 660mg/day# None Reduced FBG and 2h-PPBS, improved motor nerve conduction velocity
Hayee et al., [41] 2005, Bangladesh R, DB, P; T2DM (n=60); age 50.9 11.1year; 3 groups; 6weeks Plasma Zinc; FBG; 2-h PPBS; Nerve conduction tests ZnSO4; 660mg/day# None Reduced FBG and 2h-PPBS, improved motor nerve conduction velocity
Hegazi et al., [42] 1992, Egypt Casecontrol; T2DM (n=56); age 26 62year; 2 groups; 3weeks FBG; Plasma Zinc; Insulin; Glucagon; Glucose-6-Phosphatase Zn3(PO4)2; 28mg/day# None Increased serum Insulin. Reduced FBG and Glucagon
Heidarian et al., [43] 2009, Iran R, DB, C; T2DM (n=50); age 53.2 9.2year; 2 groups; 3months Plasma Zinc; Folate; Vitamin B12; Homocysteine ZnSO4; 30mg/day# None Reduced serum Homocysteine, increase folate and Vitamin B12
Hussain et al., [34] 2006, Iraq R, DB, P; T2DM (n=46); age 49.1 6.0year; 3 groups; 3months FBG; 2-h PPBS; HbA1c; C-Peptide Zn acetate; 50mg/day# Melatonin Reduced FBG and 2-h PPBS
Kadhim et al., [35] 2006, Iraq R, DB, P; T2DM (n=46); age 49.1 6.0year; 3 groups; 3months TC; TG; HDL-c; LDL-c; Creatinine; Urea; Urinary Microalbumin Zn acetate; 50mg/day# Melatonin Reduced TC, TG and LDL
Niewoehner et al., [44] 1986, USA Cohort study; T2DM (n=13); age 61.0 2.0year; 2 groups; 68weeks Plasma Zinc; HbA1c; Immune function ZnSO4; 660mg/day# None No beneficial effects observed
Parham et al., [36] 2008, Iran R, DB, C; T2DM (n=39); age 53.2 9.2year; 2 groups; 6months FBG; HbA1c; GFR; SBP; DBP; TC; TG; HDL-c; LDL-c; Urinary Albumin; Plasma Zinc ZnSO4; 30mg/day* None Reduced urinary albumin excretion
Partida-Hernndez et al., [37] 2006, Mexico R, DB, C; T2DM (n=27); age 35 65year; 2 groups; 4months FBG; HbA1c; Plasma Zinc; TG; TC; LDL-c; HDL-c ZnSO4; 100mg/day# None Reduced TC and TG. Increased HDL
Raz et al., [45] 1989, Israel Cohort study; T2DM (n=13); age 55.0 2.4year; 1 group; 2months Plasma Zinc; FBG; Fructosamine; HbA1c; TC; TG; HDL-c; immune function; IV GTT ZnSO4; 660mg/day# None Increased glucose intolerance
Roussel et al., [46] 2003, Tunisia R, DB, P; T2DM (n=56); age 53.6 1.5year; 2 groups; 6months Plasma and Urinary Zinc; Antioxidant effects Zn gluconate 30mg/day* None Positive antioxidant effect
Seet et al., [47] 2011, Singapore R, B, P; T2DM (n=40); age 56.0 7.5year; 2 groups; 3months FBG; Insulin; TC; LDL-c; HDL-c; TAG; PAF-AH; PLA2 Zn gluconate; 240mg/day# None No beneficial effects observed
Shidfar et al., [18] 2010, Iran R, DB, P; T1DM (n=48); age 720year; 2 groups; 3months BMI; Apo A-1 and B; FBG; Insulin ZnSO4; 10mg/day* Vitamin A Increase in serum Apo-A1 and Decrease in Apo-B/Apo-A1 ratio
  1. ALT-Alanine Aminotransferase; AST-Aspartate Aminotransferase; BMI-Body Mass Index; B-Single blinded; C-Cross over; DB-Double Blinded; FBG-Fasting Blood Glucose; HbA1c-Glycated haemoglobin; HDL-c-High Density Lipoprotein-Cholesterol; IGF1-Insulin Like Growth Factor-1; IOP-Intra Ocular Pressure; IV GTT-Intravenous Glucose Tolerance Test; LDL-c-Low Density Lipoprotein-Cholesterol; MAP-Mean Arterial Pressure; P-Parallel; RRandomized; T1DM-Type 1 Diabetes; T2DM Type 2 Diabetes; TC-Total Cholesterol; TG-Triglycerides;
  2. Age presented as meanSD in years where data were available and as age range in other studies; * - Elemental Zinc dose supplemented per day, # - Dosage given as formulations