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. 2019 Dec 3;2019(12):CD008558. doi: 10.1002/14651858.CD008558.pub2

Comparison 1. Metformin versus placebo or diet and exercsie.

Outcome or subgroup title No. of studies No. of participants Statistical method Effect size
1 All‐cause mortality 5 2833 Risk Ratio (M‐H, Random, 95% CI) 1.11 [0.41, 3.01]
2 Incidence of type 2 diabetes 12 3632 Risk Ratio (M‐H, Random, 95% CI) 0.50 [0.38, 0.65]
3 Incidence of type 2 diabetes (blinded vs open‐label) 12 3632 Risk Ratio (M‐H, Random, 95% CI) 0.50 [0.38, 0.65]
3.1 Participants blinded 2 2240 Risk Ratio (M‐H, Random, 95% CI) 0.74 [0.64, 0.86]
3.2 Open‐label 10 1392 Risk Ratio (M‐H, Random, 95% CI) 0.40 [0.27, 0.59]
4 Incidence of type 2 diabetes (duration of the intervention) 12 3632 Risk Ratio (M‐H, Random, 95% CI) 0.50 [0.38, 0.65]
4.1 Duration of the intervention less than 2 years 4 296 Risk Ratio (M‐H, Random, 95% CI) 0.30 [0.14, 0.66]
4.2 Duration of the intervention 2 years or more 8 3336 Risk Ratio (M‐H, Random, 95% CI) 0.53 [0.40, 0.71]
5 Incidence of type 2 diabetes (ethnicity) 12 3632 Risk Ratio (M‐H, Random, 95% CI) 0.50 [0.38, 0.65]
5.1 mainly White 1 2155 Risk Ratio (M‐H, Random, 95% CI) 0.75 [0.65, 0.87]
5.2 mainly Asian 10 1418 Risk Ratio (M‐H, Random, 95% CI) 0.41 [0.28, 0.59]
5.3 Other 1 59 Risk Ratio (M‐H, Random, 95% CI) 0.34 [0.01, 8.13]
6 Non‐serious adverse events 2 285 Risk Ratio (M‐H, Random, 95% CI) 3.86 [0.18, 83.36]
7 2‐hr glucose values 13 3346 Mean Difference (IV, Random, 95% CI) ‐0.86 [‐1.26, ‐0.46]
8 2‐hr glucose values (blinded vs open‐label) 13 3346 Mean Difference (IV, Random, 95% CI) ‐0.86 [‐1.26, ‐0.46]
8.1 Participants blinded 4 2032 Mean Difference (IV, Random, 95% CI) ‐0.26 [‐0.86, 0.33]
8.2 Open‐label 9 1314 Mean Difference (IV, Random, 95% CI) ‐1.03 [‐1.35, ‐0.71]
9 2‐hr glucose values (duration of intervention) 13 3346 Mean Difference (IV, Random, 95% CI) ‐0.86 [‐1.26, ‐0.46]
9.1 Duration of intervention less than 2 years 4 286 Mean Difference (IV, Random, 95% CI) ‐1.37 [‐1.91, ‐0.82]
9.2 Duration of intervention 2 years or more 9 3060 Mean Difference (IV, Random, 95% CI) ‐0.75 [‐1.18, ‐0.33]
10 2‐r glucose values (ethnicity) 13 3346 Mean Difference (IV, Random, 95% CI) ‐0.86 [‐1.26, ‐0.46]
10.1 Mainly White 1 1856 Mean Difference (IV, Random, 95% CI) 0.0 [‐0.17, 0.17]
10.2 Mainly Asian 10 1384 Mean Difference (IV, Random, 95% CI) ‐1.05 [‐1.35, ‐0.75]
10.3 Other 2 106 Mean Difference (IV, Random, 95% CI) 0.05 [‐0.69, 0.79]
11 HbA1c (blinded vs open‐label) 6 2467 Mean Difference (IV, Random, 95% CI) ‐0.08 [‐0.22, 0.05]
11.1 Participants blinded 2 1926 Mean Difference (IV, Random, 95% CI) 0.0 [‐0.04, 0.04]
11.2 Open‐label 4 541 Mean Difference (IV, Random, 95% CI) ‐0.35 [‐0.77, 0.08]
12 HbA1c (duration of intervention) 6 2467 Mean Difference (IV, Random, 95% CI) ‐0.08 [‐0.22, 0.05]
12.1 Duration of intervention less than 2 years 3 269 Mean Difference (IV, Random, 95% CI) ‐0.15 [‐0.50, 0.21]
12.2 Duration of intervention 2 years or more 3 2198 Mean Difference (IV, Random, 95% CI) ‐0.26 [‐0.75, 0.22]
13 HbA1c (ethnicity) 6 2467 Mean Difference (IV, Random, 95% CI) ‐0.08 [‐0.22, 0.05]
13.1 Mainly White 1 1856 Mean Difference (IV, Random, 95% CI) 0.0 [‐0.04, 0.04]
13.2 Mainly Asian 4 556 Mean Difference (IV, Random, 95% CI) ‐0.45 [‐0.74, ‐0.16]
13.3 Other 1 55 Mean Difference (IV, Random, 95% CI) 0.0 [‐0.11, 0.11]
14 Fasting plasma glucose 15 3546 Mean Difference (IV, Random, 95% CI) ‐0.28 [‐0.42, ‐0.13]
15 Fasting plasma glucose (blinded vs open‐label) 15 3546 Mean Difference (IV, Random, 95% CI) ‐0.28 [‐0.42, ‐0.13]
15.1 Participants blinded 4 2037 Mean Difference (IV, Random, 95% CI) ‐0.51 [‐0.94, ‐0.09]
15.2 Open‐label 11 1509 Mean Difference (IV, Random, 95% CI) ‐0.22 [‐0.42, ‐0.03]
16 Fasting plasma glucose (duration of the intervention) 15 3546 Mean Difference (IV, Random, 95% CI) ‐0.28 [‐0.42, ‐0.13]
16.1 Duration of the intervention less than 2 years 6 485 Mean Difference (IV, Random, 95% CI) ‐0.51 [‐0.89, ‐0.13]
16.2 Duration of the intervention 2 years or more 9 3061 Mean Difference (IV, Random, 95% CI) ‐0.19 [‐0.35, ‐0.02]
17 Fasting plasma glucose (ethnicity) 15 3546 Mean Difference (IV, Random, 95% CI) ‐0.28 [‐0.42, ‐0.13]
17.1 Mainly White 1 1861 Mean Difference (IV, Random, 95% CI) ‐0.30 [‐0.39, ‐0.21]
17.2 Mainly Asian 11 1524 Mean Difference (IV, Random, 95% CI) ‐0.31 [‐0.51, ‐0.11]
17.3 Other 3 161 Mean Difference (IV, Random, 95% CI) ‐0.14 [‐0.49, 0.22]