I don't know the elevation at Leh but in general, you should be fine if you make your assent slowly. Maybe stay in Delhi a day or two before going on to Leh if possible, so your body can be fresh to deal with the change in altitude. Also, leave out the caffeine and drink plenty of water. It really does help. Then once you get there, take it easy for a couple days.

The efficacy of Diamox varies from person to person, as does getting altitude sickness and its severity. I found Diamox helpful in Tibet.

I had no problems in Leh, though I went there by Bus. We had to spend the night at a place much higher than Leh. And there I had some problems. But really nothing serious. Just keep it slow for the first one or two days.

I'll be in Leh June or July, maybe I'll see you there. It's such a great place!

go to old manali, smoke chadras for a day or two.....its at 2000+ meters....

I think if you are going to take Diamox you are supposed to start a couple days before your trip... just so you know.

Rule of thumb is +1000 m per day for 2 days, rest 1 day, then another 1000m.

Every person is different and will start to become sick at different levels.

Headache 1st sign, Nausea 2nd sign... expect your breathing frequency to be increased already

If you get a headache, (a bad one), eat some garlic soup... wait a couple hours... if you are not getting better, or are getting worse... think seriously about seeing a doctor for evaluation, or start heading down...

just my 2 cents