If you are already producing no insulin when you are diagnosed, Type 1 isn’t necessarily progressive. If you’re already producing zero insulin, you can’t produce less! Your insulin dosages may change according to your stage in life. For example, teenagers often need huge doses when going through puberty. Or pregnant women may need much less insulin for part of the pregnancy and then huge doses at other stages of the pregnancy. But if you start at a dosage that works well with you, then hypothetically it could continue to be correct for a long period of time. Some people find that there doses change often, but others are quite stable.
I was diagnosed in the 70’s and started on one shot a day. As newer insulins were introduced and then when I went on the pump, my dosages changed quite a bit. I take much less insulin than I used to. Also, since I try to eat relatively low carb, my mealtime insulin is much less.
Type 2 is more of a progressive disease than Type 1. Many people with Type 2 are able to control their disease with no meds or just orals early in their disease. My understanding is that most people with Type 2 eventually have to take higher doses of medications and many/most long-term Type 2’s eventually end up on insulin. It’s not that they’ve failed to control their diabetes; it’s just that the disease has progressed.