I get tired eyes. Could this be related to diabetes?

Glucose or Dry eyes. Glucose fluctuations can change vision the increased glucose in his blood also increases the glucose inside the lens in the eye. The lens with high glucose draws fluid via osmosis. This fluid increases the thickness of the lens, therefore; the power of the lens. The change in power may allow the patient to see better at near or better at distance. Also diabetes can lead to dry eye due neuropathy.
It's possible. If you are diabetic, you are more susceptible to dry eyes and blurred vision. Both of these can make the eyes feel tired. Tired eyes do not necessarily mean diabetes, but if you have a family history or have other concerns, you should be evaluated by your doctor.