Hello I Had A Question About My Partners ED. He

Hello I had a question about my partners ED. He was diagnosed with Type 2 Diabetes over a year ago. He is only 30 years old, very fit (minimal fat) and eats a very healthy diet with very little sugar. He started off vomiting up to 7 times a day, he had no appetite and could barely eat anything resulting in dramatic weight loss from 13 stone to 11 stone. A couple of months later he started to get erectile problems. He has not had an erection for over 2 years now. The next symptom he had was blurred vision and a lesser sensation in his right big toe. He was then diagnosed with T2 Diabetes. He has had several blood tests, his testosterone is fine. He has also had a doppler done which showed blood flow to the area as fine. He has started to get some sensation back to his penis but he still doesn't get harder than a semi and there seems to be little pre-ejaculate. He also states that there 'isn't any feeling which is relayed from his brain to his penis'. Although his sugar levels have come down to 44, his vision and ED have not rectified. He is also unable to eat sweet things which he could 2 years ago. He has seen endocrinologists, urologists and opthamologists etc but to no avail. Any ideas what the issue could be? It doesn't seem to be as straight forward as T2 Diabetes as these symptons usually occur decades after an individual has been diagnosed. Thank you