Elevated ANA and ACE, and sural nerve biopsy - can anyone advise?

[crabb]

Hi
I'm 59yo, obese, and have type 2 diabetes.
I developed what is probably peripheral neuropathy in my feet last year. In January this year I had a brief episode of amnesia. Due to these issue I've seen a neurologist, who stated the foot issue was highly likely to be due to the diabetes, but sent me for a battery of blood tests, a brain MRI, an EEG, and a nerve conduction study to investigate everything more thoroughly.

EEG and MRI were clear and he's happy that the event in January was transient global amnesia. However, the nerve conduction study showed more damage than would be expected "evidence of sensorimotor axonal neuropathy", and the blood tests showed elevated ANA titre of 640, and ACE of 122 U/L (cutoff 55).

He is now suspicious of autoimmune inflammatory causes - maybe sarcoid or lupus? This week I've had a Gallium scan and a chest CT to look for "pulmonary involvement". I've seen the results - nothing has turned up. His next option is a sural nerve biopsy, which he told me carried risks.

So, has anyone had experience of similar? What are the ANA and ACE pointing to if not sarcoid? Is it definite I have an automimmune condition?What is the sural nerve biopsy looking for? Anything treatable? Should I undertake it? My short bit of googling indicates many patients can suffer a worsening of symptoms after it.

My next neuro follow up appointment is in 3 weeks and I'd like to be prepared, this is all new to me and I'm a bit worried