Yes, there is no harm to be tested for diabetes given your symptoms, your age, and the fact that you are overweight. In fact, people at 50 should be screened for diabetes.
The appropriate tests are Fasting Blood Sugar (FBS) and Hba1c (this gives an average of 3 months blood sugar. Normal fasting levels are in the 80s, though the lab will tell you up to 95 or so is normal. Normal hba1c is < 5.0 (though the lab will tell you up to about 5.7 is normal).
Go get tested, and come back and let us know.
A lower carb way of eating such as mediterranean (limit the bread and pasta) or Paleo can be very helpful in helping with both weight management and preventing / treating type 2 diabetes.
I have been dieting. I never been heavy my whole life, even after I gave birth after 40 I was wearing a swimsuit 1 month after. it was my last baby when I was almost 44 and my weight kept going up and being hit with menopause on top of it, it's been a downhill battle for me.
You should be checked for thyroid. This is a major cause of weight gain. the proper tests are FT3, FT4 and TSH.
You should also have testing for diabetes.
Low carb (not low fat) should be the way to go for weight loss. Please look into this further.