Diabetes can and does cause a form of dementia that is very similar to Alzheimer's but that takes a number of years to develop and only comes about due to very high (uncontrolled) blood sugars for a number of years.

Just looking at your story you haven't had Diabetes long enough for it to be the "likely cause" although it could certainly contribute if there was some other medical/physiological reason causing it.

But as Rosemary points out, having things "slip your mind" is also simply a part of natural aging. All of our thought process and movement process for that matter rely on the production of hormones/chemicals in the brain and they do "naturally decline" as we get older.

However, if you are becoming concerned you can bring it up to your doctor. There are some (tests) that they can do to see if there is a "treatable cause".