Type 2 diabetes is the most common diabetes diagnosis. It is sometimes diagnosed in childhood (although not in very young children) and the risk of being diagnosed goes up with age until, depending on the country we're talking about, somewhere between the ages of 70 and 90, although average fasting blood sugar does seem to increase even after the age of 70.
Type 2 diabetes is a major risk factor for dying younger when it's diagnosed in children, young adults, and the middle aged, but in the elderly its a much smaller risk factor, and numerous studies of very old people have found that it's not a risk factor at all until you start adjusting for various things, particularly BMI (diabetics tend to have higher BMIs, and in people above about 85, the higher the BMI, the lower the risk of death). In fact, in a number of studies on people above the age of 85, being diabetic was associated with a lower risk of death in a short period (2-5 years).
To me, the Georgia Centennarian Study (Georgia as in the southern state, not the country) is particularly interesting. Among the 244 people they studied, age 98 to 108, 21 of the 244 had been diagnosed with diabetes and another 8 people had high A1cs or random blood sugar and were diagnosed as part of the study. Although only 7 of them were diagnosed before the age of 80, 1 had been diagnosed with diabetes more than 50 years earlier.
After 1 year, 20% of the diabetics died and 27% of the non-diabetics died. The diabetics did not have a higher risk of vision loss or a higher risk of diagnosed neuropathy.