Glucose tolerance tests

Hi I'm 26 wks pregnant with twins and already have had to do 3 glucose tolerance tests as every time I go to clinic dere is a trace of sugar in my urine. I rarely eat chocolate and don't drink fizzy drinks or eat sweets or add sugar in any foods. It just seems dat my kidneys under slight pressure and leak a little sugar. However hospital want me to do a 4th glucose tolerance test in 2 wks wen I will be 28th weeks. I'm worried dat all dis fasting and den drinking pile of lucozade the worst drink you could take is bad for babies doing it so much. Has anyone else had to go through this and if so were the babies ok??