When a placebo is not a 'placebo': a placebo effect on postprandial glycaemia.
OBJECTIVE
Placebo effects in clinical trials remain uncertain. To investigate a placebo effect on acute postprandial plasma glucose, we conducted a follow-up investigation on a previous study.


METHODS
The effect of placebo (9 g encapsulated cornstarch +500 ml water, taken at -40 min) on the plasma glucose response to a 75-g oral glucose tolerance test (OGTT) was assessed in a previous study in 12 healthy subjects (gender, five male, seven female; age 27 +/- 6 years; body mass index 24 +/- 3.4 kg m(-2)). This was compared with the effect of a water control (500 ml water taken alone at -40 min) on the same outcome in the same subjects in a follow-up study.


RESULTS
Cornstarch placebo decreased plasma glucose area under the curve during the 75-g OGTT by 28% [Delta (95% confidence interval) -63.3 min mmol(-1) l(-1) (-218.33, 91.66), P < 0.02] compared with the water control (P < 0.05).


CONCLUSIONS
Postprandial plasma glucose outcomes may be vulnerable to placebo effects.
Sievenpiper
John L
JL
Risk Factor Modification Centre, St Michael's Hospital and Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
Ezatagha
Adish
A
Dascalu
Anamaria
A
Vuksan
Vladimir
V
D000328:Adult; D000704:Analysis of Variance; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D005951:Glucose Tolerance Test / Q000379:methods*; D038321:Glycemic Index / Q000502:physiology*; D006801:Humans; D008297:Male; D010865:Pilot Projects; D015990:Placebo Effect; D019518:Postprandial Period / Q000502:physiology*; D013213:Starch / Q000008:administration & dosage / Q000378:metabolism*
D001786:Blood Glucose; D013213:Starch