Zeller 1991.

Methods	RCT . Mean duration 35 months , minimum 12 months.
Participants	47 type 1 patients with proteinuria over 500mg/24 hours , with diabetic retinopathy and no other cause of renal failure . LPD mean age 33. Mean duration of diabetes 21 years. UPD mean age 35. Mean duration of diabetes 22.4 years.
Interventions	LPD = 0.6g / kg / ideal body weight/day (n=20). UPD = at least 1 g/kg/day (n=15).
Outcomes	GFR by iothalamate and creatinine. Malnutrition measured by weight, mid‐arm circumference, and serum albumin. Compliance assessed by uU and dietary history. Actual protein intake 0.72 g/kg/day.
Notes	Malnutrition measures showed no significant change.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	B ‐ Unclear

LPD: Low protein diet 
 UPD: Usual protein diet 
 EAA: Essential amino acids 
 TST: Triceps skinfold thickness 
 MAMC: Middle arm muscle circumference 
 GFR: Glomerular filtration rate 
 BMI: Body mass index 
 RR: Relative risk 
 ESRD: End‐stage renal disease 
 ACE: Angiotensin converting enzyme 
 RCT: Randomised controlled trial 
 Wt: Weight