My mother-in-law is 75 years old and will only drink Diet Coke. No water, no tea, no juice, no milk. She will tell you, almost bragging, that she hasn't had milk in 50 years. She suffers from stenosis of the spine, has weak pelvic/hip muscles and can't stand upright. She is also incontenent. The medication she takes requires she drink plenty of water when she takes them, and throughout the day. Her urine is so concentrated, the smell is overwhelming. I have offered to make her hot tea, bring her glass of sweet tea, orange or apple juice, etc. She ONLY wants Diet Coke. Would it be terrible of me to just quit buying it? She refuses to discuss it!