Table 2

Summary of findings

OutcomesNo. of participants
(studies) followed up
Certainty of the evidence
(GRADE)
Anticipated absolute effects
Risk with the carbohydrate-first meal pattern or random meal sequenceRisk difference with the carbohydrate-later meal pattern§
HbA1c concentrations (NGSP)147
(3 RCTs)
⊕⊕ □ □
Low*†
The mean HbA1c (%) ranged from 6.1% to 7.7%MD 0.21% lower
(0.44 lower to 0.03 higher)
Physical component summary score (SF36, SF12, SF8)NR
Mental component summary score (SF36, SF12, SF8)NR
Plasma glucose 120 min after meals143
(6 RCTs)
⊕⊕ □ □
Low*†
Mean plasma glucose (mg/dL) 120 min after all meals ranging from 97.1 to 281.5 mg/dLMD 4.94 mg/dL higher
(8.34 lower to 18.22 higher)
Plasma insulin 120 min after meals136
(5 RCTs)
⊕⊕ □ □
Very low*†‡
Mean plasma insulin (μIU/mL) 120 min after meals ranging from 6.6 to 94.5 μIU/mLMD 3.63 μIU/mL lower
(11.88 lower to 4.61 higher)
Plasma GLP-1 120 min after meals76
(3 RCTs)
⊕⊕ □ □
Low*†
Mean plasma GLP-1 (pmol/L) 120 min after meals ranging from 3.2 to 22.3 pmol/LMD 0.43 μIU/mL higher
(0.69 lower to 1.56 higher)
Plasma GIP 120 min after meals44
(2 RCTs)
⊕⊕ □ □
Low*†
Mean plasma GLP-1 (pmol/L) 120 min after meals ranging from 24.1 to 76.5 pmol/LMD 2.02 μIU/mL lower
(12.34 lower to 8.31 higher)
All adverse eventsNR
  • GRADE Working Group grades of evidence.

  • High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is markedly different. Low certainty: our confidence in the effect estimate is limited: the true effect may be markedly different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be markedly different from the estimate of the effect.

  • *Downgraded due to the risk of bias.

  • †The sample size was small. The sample size did not meet the criteria of the optimal information size (OIS) (400). OIS was 400 if alpha D0:05, beta D0:2, delta D0:2.

  • ‡The I2 statistic was higher than 60%, showing great heterogeneity and the direction of the effect was different.

  • §The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

  • GIP, glucose-dependent insulinotropic polypeptide; GLP-1, glucagon-like peptide-1; GRADE, Grading of Recommendations Assessment, Development and Evaluation; HbA1c, hemoglobin A1c; MD, mean difference; NGSP, national glycohemoglobin standardization program; NR, not reported; RCTs, randomized controlled trials; SF, short form.