data <- matrix(scan(),ncol=3,byrow=TRUE)
 1 1 42.5  1 1 43.3  1 1 42.9  1 2 42.2  1 2 41.4  1 2 41.8 
 2 3 48.0  2 3 44.6  2 3 43.7  2 4 42.0  2 4 42.8  2 4 42.8 
 3 5 41.7  3 5 43.4  3 5 42.5  3 6 40.6  3 6 41.8  3 6 41.8 

data
table77  <- data.frame(data)
colnames(table77)  <- c("day","run","glucose")
rm(data)

table77$day  <- as.factor(table77$day)
table77$run  <- as.factor(table77$run)

aov(glucose ~ day + Error(day/run), data = table77)

 # or instead use

aov(glucose ~ day + run %in% day, data = table77)