The Effect of Metformin on Adolescents with Type 1 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Table 1

Study design and baseline characteristics of the included studies.

Study and publication year	Study design	T1DM duration, y		Sample size		Male		Age, y		BMI, kg/m^2		HbA1c, %		Duration of therapy	Final dose of metformin per day	Target participants
		Met	PL	Met	PL	Met	PL	Met	PL	Met	PL	Met	PL
Libman et al., 2015 [15]	Multicenter, double-blind RCT	7.5 (3.6)	6.4 (3.0)	71	69	27	21	15.4 (1.7)	15.1 (1.8)	1.6^# (0.4)	1.7^# (0.3)	8.8 (0.8)	8.8 (0.7)	26 weeks	2000 mg	Overweight/obese adolescents
Nwosu et al., 2015 [13]	Single-center, double-blind RCT	5.7 (4.4)	5.7 (5.0)	15	13	8	5	15.0 (2.5)	14.5 (3.1)	28.0 (5.4)	27.7 (4.1)	9.3 (1.5)	8.7 (0.4)	9 months	1000 mg	Overweight/obese adolescents
Nadeau et al., 2015 [14]	Single-center, double-blind RCT	6.7 (3.6)	6.3 (3.5)	40	40	59% males in total		15.9 (1.7)	16.0 (1.6)	23.5 (3.0)	24.3 (4.1)	9.5 (1.3)	9.4 (1.1)	6 months	1000 mg	General adolescents
Särnblad et al., 2003 [6]	Multicenter, double-blind RCT	9.1 (5.0)	7.1 (3.0)	13	13	5	4	17.2 (1.7)	16.9 (1.4)	23.5 (18.6–35.4)	23.9 (17–29.2)	9.6 (1.0)	9.5 (1.2)	3 mouths	2000 mg	General adolescents
Hamilton et al., 2003 [17]	Single-center, double-blind RCT	9.9 (4.4)	7.0 (3.8)	14	13	6	7	15.9 (1.9)	16.0 (1.7)	22.8 (4.2)	25.7 (2.9)	9.3 (1.4)	8.6 (0.8)	3 months	1000 mg, 1500 mg, or 2000 mg according to body weight	General adolescents

BMI was calculated using height and weight and adjusted for age and sex using growth chart tables obtained from the centers for disease control and prevention. BMI -scores were used in this study. The data are shown as the median (range).
Data are shown as numbers or means (SD) unless otherwise indicated. RCT: randomized controlled trial; T1DM: type 1 diabetes mellitus; HbA1c: hemoglobin A1c; BMI: body mass index; Met: metformin; PL: placebo.