Constant thirst 38 weeks pregnant

since I was around 35 weeks pregnant I've become so thirsty and drinking around 10 bottles of water a day I'm concerned because I know drinking to much water is bad for you as your kidneys can't process it quick enough i get my urine checked for protein and it comes back clear every time doesn't it sound like I could have diabetes or is this just a pregnancy thing? I wake up during the night for a drink and take a bottle to bed with me and nearly finish it by the morning