Forum newbie concerned i may have diabetes

Hi everyone, not used to forums so bear with me. I am 52 and have recently been getting fluctuating BS readings from 3.2 am to 10.2 at night. Past med history had 12ft of short bowel removed at 23 years due to blood clot. maintaining weight difficult due to malabsorption, Advice given by bowel Consultants, no fiber, plenty of high calorie and fatty foods...this resulted in me developing a very sweet tooth and living predominately on tea, toast and chocolate. Currently take thyroxine, on HRT as well as morphine for long term chronic pain for osteoarthritis. Weight has been fairly stable until l hit the menopause, approx 12lbs overweight but BMI normal. Pain consultant mentioned that I may be ?insulin resistant, not entirely sure what this means but am feeling so tired all the time. I'm sure my poor diet over 30 years has not helped but wondering why i am getting these high readings now.
I would be really grateful if anyone could shed any light on whats going on. Thank you.

Thanks for your reply , will go to GP when they have an appointment especially as been between 3 to 5mmol today and l have just wanted to sleep all day. Thanks Cezzie