Table 2—

Methodological quality of RCTs in diabetes

Patient-important outcomesSurrogate outcomesPhysiological and other laboratory outcomesOverall
n4238119199
Study characteristics
    Parallel/cross-over trials36/631/778/41145/54
    Study duration (weeks)
        Parallel trials136 (26–235)33 (24–129)16 (10–48)26 (12–104)
        Cross-over trials24 (5–42)16 (1.3–51)12 (2.6–24)13 (3–27)
    Randomized
        Parallel trials474 (162–1,513)160 (46–404)54 (37–105)97 (46–327)
        Cross-over trials23 (20–27)35 (22–63)16 (9–27)20 (11–32)
Reporting
    Patient flow chart14 (33)8 (21)18 (15)40 (20)
    IRB approval, informed consent40 (95)37 (97)115 (97)192 (97)
    Estimation of sample size25 (60)19 (50)34 (29)78 (39)
    Adverse events reported16 (38)21 (55)64 (54)101 (51)
Methods to minimize bias
    Adequate allocation concealment9 (21)4 (11)8 (7)21 (11)
    Blinding
        Participants20 (48)17 (45)62 (52)99 (50)
        Health care providers19 (45)20 (53)52 (44)91 (46)
        Data collectors9 (21)3 (8)11 (9)23 (12)
        Data analysts3 (7)1 (3)7 (6)11 (6)
        Judicial assessors of outcomes8 (19)1 (3)8 (7)17 (9)
        Only described as double blind16 (38)16 (42)57 (48)89 (45)
    Intention-to-treat analysis27 (64)22 (58)22 (18)71 (36)
    Loss to follow-up
        Parallel trials (%)4 (0–24)9 (2–20)5 (0–14)5 (0–17)
        Cross-over trials (%)3 (0–19)0 (0–1)0 (0–0)0 (0–2)
        Not reported10 (24)10 (26)37 (31)57 (29)
Low methodological quality15 (36)15 (40)76 (64)106 (53)
  • Data are median (interquartile range) or n (%) unless otherwise indicated. IRB, institutional review board.