I'll second that - from experience. At 59, I had the same thing happen (on a business trip, not a hiking trip), and was diagnosed with Type II diabetes. (If that is the problem, don't despair - you may be able to control it with diet and exercise, though you may need medication for a while. And it definitely doesn't end your hiking days - you'll have to take more care with diet, but I'm here to tell you it's extremely possible.

OM: if midnight calls are a women's problem, then (to paraphrase a non-PC punch line) bring us girls a bottle of water!