The hormone therapies increase your underlying risk of developing diabetes. A 2016 study found tamoxifen increased the risk by 2.2 times while letrozole (and other aromatase inhibitors) increased the risk by 4.3 times. I've been on letrozole for 2.5 years and am now pre-diabetic, despite eating a healthy diet and exercising regularly. I'm on statins for high cholesterol, which is made worse by letrozole (and other aromatase inhibitors). Statins also increase the risk of developing diabetes. I'm now on metformin to reduce my risk of progressing to diabetes. I suggest talking to your doctor about options for reducing your risk of developing diabetes while on exemestane.
I just started taking Exemestane and I see my blood pressure and sugar is elevated.