Metformin fails to prevent diabetes in non-diabetic cardiovascular patients: Systematic review and meta-analysis

Table 4 Efficacy and safety of metformin’s included interventions in preventing type-2 diabetes

Overall effectiveness and safety of metformin
Ref.	Outcome of T2DM assessed as primary or secondary	Participants at risk for T2DM (I/C)	Events of T2DM n (%) (I/C)	Diagnostic modalities	Total adverse events, side effects, n (%) (I/C)
Preiss et al[22], 2014	Secondary	86/87	2 (2)/6 (7)	HbA1c	Gastrointestinal symptoms 28 (32.6)/5 (5.7), CVD events 7 (8.1)/16 (18.4), newly diagnosed neoplasm 1 (1.0)/4 (5.0), deaths 1 (1.0)/0 (0.0)
Lexis et al[23], 2015	Secondary	162/156	20 (12.3)/18 (11.5)	FPG, 2 hours 75 g OGTT, HbA1c	NR
Hartman et al[24], 2017	Secondary	191/188	34 (17.8)/32 (17.0)	HbA1c	NR
Mohan et al[25], 2019	Secondary	31/32	0 (0)/1 (3.1)	FPG, HbA1c	Mild-to-serious gastrointestinal symptoms 24 (70.6)/19 (55.9), stroke 1 (2.9)/0 (0.0)

T2DM: Type-2 diabetes mellitus; I: Intervention; C: Comparator; HbA1c: Hemoglobin A1c; CVD: Cardiovascular disease; FPG: Fasting plasma glucose; OGTT: Oral glucose tolerance test.