Is glaucoma caused by diabetes?

Sometimes. Large studies published suggest that diabetes and primary open angle glaucoma (poag) are not related. Then other studies suggest that diabetes and poag are related. Without a doubt neovascular glaucoma and diabetic diabetes are related. Easy thing to do is when you get your diabetes exam. Ask your doctor to examine you for both glaucomas. By the way normal eye pressure does not exclude disease.
No. However, vascular problems such as diabetes can cause neovascularization of the angle or drain of the eye, thus leading to elevated eye pressure and secondary glaucoma. Diabetes is the most common cause of neovascular glaucoma.
No. It is important to separate cause and effect from association. It is probably true that the incidence of glaucoma among diabetics is higher. The same holds true for hypertension. Glaucoma may occur at a high rate in diabetics, but the diabetes doesn't cause glaucoma usually.