There seems to be no scientific evidence to support the claim that diabetes type 2 generally goes away on its own (without drugs, diet or weight loss) in the elderly.
According to one analytical article in BMJ, 2017, remission of diabetes type 2 is "currently very rarely achieved or recorded."
In elderly, remission may be slightly more common. In a large cohort study (Diabetes Care, 2014), "1.5% of individuals with diabetes type 2 not treated with bariatric surgery or drugs (but treated with diet or weight loss) achieved at least partial remission over a 7-year period. Remission occured in 2.2% of individuals 65 years or older (table 4).
In one randomized clinical trial (PubMed, 2012), intensive lifestyle intervention, including exercise, diet and weight loss, resulted in at least partial remission in 11.5% of individuals with diabetes type 2 within the 1st year of the intervention.