Table 1.

Study visit schedule

Study phase	Metformin run-in (3 months)							Study treatment follow-up (24 months)
Time point	Wk 0	Wk 2	Wk 4	Wk 6	Wk 8	Wk 10	Wk 12/	Mth 0	Mth 1	Mth 3	Mth 6	Mth 12	Mth 18	Mth 24
Location	Clinic	Phone	Clinic or remote	Phone	Clinic or remote	Phone	Clinic†		Phone	Clinic or remote	Clinic or remote	Clinic	Clinic or remote	Clinic
Screening
Eligibility	X							X
Informed consent	X
Medical history	X
Clinical assessments
Concomitant medications	X	X	X	X	X	X		X	X	X	X	X	X	X
Physical examination	X							X				X		X
Blood pressure	X		X		X			X		X	X	X	X	X
GSRS*	X							X				X		X
EQ-5D-5L	X							X				X		X
ADPKD-PDS	X							X				X		X
Adverse events (as required)		X	X	X	X	X		X	X	X	X	X	X	X
Local lab assessments
Full blood count, biochemistry	X							X				X		X
Vitamin B12 test	X
Urine assessments	X							X				X		X
Urine osmolality test	X							X				X		X
Creatinine test‡			X		X
Pregnancy test≠	X							X				X		X
Central lab assessments∆
Cystatin C	X							X				X		X
Medication related
Dispense medication	X							X			X	X	X
Randomization								X
Return and count unused medication								X			X	X	X	X

^†Wk 12 and Mth 0 occur concurrently. ^*Can be conducted at any time only if Participant reports gastrointestinal symptoms. ^‡Creatinine test to determine eGFR during run-in phase to monitor safety. At other time points, eGFR is tested as part of routine local laboratory assessment. ^≠Only for female participants of childbearing age. ^ΔCentral lab assessments for sites with sample processing and storage facility