How Much Water Should You Be Drinking?

Thirst and passing more urine than usual are two of the commonest symptoms of diabetes, and they are connected: when there is too much glucose in your blood, your kidneys pull water out of you to get rid of it.

That is why a run of high readings leaves you thirsty, and why the thirst is a symptom rather than a coincidence. Drinking water does not treat the high — but being dehydrated on top of it makes you feel considerably worse and concentrates the glucose further.

Practical guidance

• Drink to thirst, and a bit before it in Indian heat, where losses are higher than most guidance assumes.
• Water, not juice. A glass of juice can carry more sugar than a meal; Diabetes UK suggests no more than 150 ml a day if you have it at all.
• More when you are ill. Illness raises blood sugar and dehydrates you at the same time.
• More when you are active, especially outdoors.
• Watch for a sudden increase in thirst. Being much thirstier than usual for several days is worth a reading and, if it persists, a call.