I suffer from sleep apnoeia despite being under-weight. I got tested by a sleep clinic (they lend you apparatus to test you at home in bed) and was eventually prescribed a helpful device to wear in my mouth at night which I wore for years. Eventually I progressed to a ventilator (superior type of CPAP machine). By then I was having over 30 "events" per hour (basically suffocating myself and then waking up to breathe). You can imagine how exhausted I felt during the day. So, quite apart from your suspected diabetes, IMO it would be well worthwhile asking for a sleep test. With the best will in the world, it will take a while to lose the excess weight. I wouldn't wait! Good luck!