Metformin toxicity: A meta-summary of case reports

Table 1 The commonly reported symptoms (mean ± SD)

Parameter	Number of patients (n = 242)
Age	59.3 (16) yr
Gender, n (%)	Females, 126 (52.1)
	Males, 115 (47.5)
	Not mentioned, 1 (0.4)
Clinical presentation, n (%)	Vomiting, 127 (52.5)
	Abdominal pain, 96 (40)
	Altered mental status, 87 (36)
	Shock, 43 (17.8)
	Breathlessness, 41 (16.9)
	Loss of consciousness, 28 (11.6)
	Anuria, 22 (8.3)
	Cardiac arrest, 5 (2)
	Others, 15 (6.2)
Comorbidities, n (%)	Diabetes, 214 (88.4)
	Hypertension, 94 (38.8)
	Coronary artery disease, 34 (14.1)
	Chronic kidney disease, 41 (16.9)
	Chronic liver disease, 6 (2.5)
	Others, 24 (9.9)
	None, 22 (9.9)
	Not mentioned, 2 (0.8)
History of psychiatric illness, n (%)	30 (12.4)
History of metformin use, n (%)	214 (88.4)
Type of ingestion, n (%)	Chronic use, 185 (76.4)
	Suicidal, 52 (21.5)
	Accidental, 3 (1.2)
	Unclear, 1 (0.4)
	Not mentioned, 1 (0.4)
Urine toxicology screen, n (%)	15 (6.2)
Time to presentation after acute intoxication (h)	10.9 ± 13.8
Hypoglycemia, n (%)	59 (24.4)
Therapies to reduce absorption, n (%)	Activated charcoal, 16 (6.6)
	Gastric lavage, 14 (5.8)
	Whole bowel irrigation, 1 (0.4)
Need for organ support, n (%)	RRT, 166 (68.6)
	Vasopressors, 142 (58.7)
	Invasive mechanical ventilation, 128 (52.9)
	Extracorporeal membrane oxygenation, 2 (0.8)
Type of RRT, n (%)	Haemodialysis, 83 (34.3)
	Continuous RRT, 60 (24.8)
	Slow low-efficiency dialysis, 13 (5.4)
	Peritoneal dialysis, 6 (2.5)
	Haem-adsorption columns, 3 (1.2)
	Plasmapheresis, 1 (0.4)
Other treatments given, n (%)	Sodium bicarbonate, 158 (65.3)
	Glucose/insulin, 15 (6.2)
	Methylene blue, 2 (0.8)
	ECMO, 2 (0.8)
	L-carnitine, 1 (0.4)
	High dose vitamin C, 1 (0.4)
Development of organ failure, n (%)	Renal, 179 (74)
	Cardiac, 144 (59.5)
	Pulmonary, 114 (47.1)
	Neurological, 88 (36.4)
	Liver, 18 (17.4)
	Haematological, 2 (0.8)
Days on RRT	3.1 ± 6.7
Days on IMV	2.2 ± 5.1
Number of sessions of RRT	2 ± 2.6
Time of initiation of RRT after presentation (h)	6.3 ± 12.7
Days in hospital	7.3 ± 11.4
Days in ICU	4.1 ± 6.6
Outcome, n (%)	Alive, 192 (79.3)
	Death, 48 (19.8)
	Not mentioned, 2 (0.8)

RRT: Renal replacement therapy; IMV: Invasive mechanical ventilation; ICU: Intensive care unit.

Table 2 Arterial blood gas parameters

Parameter	Mean	Standard deviation	Range
pH, at presentation	7.00	0.11	6.38-7.5
Lactates, at presentation (mmol/L)	15.7	7.6	2.1-40.2
Bicarbonate, at presentation (mmol/L)	7.7	6	1–23.7
Anion Gap, at presentation	32	10.8	10-61
Lowest pH reported	6.97	0.22	6.28–7.5
Highest lactates reported (mmol/L)	18	8.6	2.4-48
Serum metformin concentration (mcg/mL)	108.7	280	0.9-2020