I'm always cold, I never used to be, I was generally just the right temperature and only really felt the heat in temps above 30 and the cold when we reached sub zero levels. Since being diagnosed with diabetes I've been a colder soul, I even wear a vest in summer and have invested in summer scarves because I get a bit chilly. There are some obvious things that should be checked medically just in case, thyroid, circulation, nerve issues (especially in the feet) so mention it to the doctor or nurse. In my case they've all been checked and all are fine but I'm still having thermostat issues. They have no idea really, the best they can come up with is that I don't have a high enough percentage of body fat for insulation and or my muscle mass percentage has changed and I ran hot prior to diabetes because I had more muscle mass, now I have less muscle so I'm running cooler 🙄
Interestingly I know I'm hypo when I'm warm, if I'm relatively OK my blood sugar is within the normal range, if I'm really cold my blood sugar is erring on the higher side. I happen to know that before I was diabetic my blood sugar ran on the low side of the normal range because it was tested (because of another condition) so I assume that's why I was cozier then. When I was first diagnosed and my blood sugar was routinely in the 20's I was frozen constantly, and my feet and hands were like blocks of ice. My consultant reckons about 25% of people with diabetes have an issue with poor temperature control with no additional circulation, thyroid or nerve involvement, so it must be commonish, although I'd still like a more precise and reassuring answer!