My understanding is diabetes is autoimmune in nature and recent studies found that autoimmune diseases (of which there are many) are made much worse by inflammatory foods. Whether a food is inflammatory or anti-inflammatory depends on what's in it. Processed foods are some of the worst offender. Wheat gluten is a big culprit as well. Many in he alternative health arenas promote organic, non-GMO, non-gluten, anti-inflammatory diets. Diets like this are difficult to maintain though and are expensive.
Personally? I would find a good nutritionist; someone that specialises in functional medicine and see what they say. They may want you to have nutrition tests, which can be expensive. You might find you need to supplement with a vitamin B complex, you might not. It's worth getting Lyme tested as well, because I've been following research that suggests autoimmune diseases may be interlinked with immunosuppresive diseases like Lyme and/or co-infections. There are many in the Lyme community that suffer neurological symptoms. You don't say whether you're being investigated at present for diabetes or whether it's a hunch (something you read online) ?
Alopathic medicine (the NHS) is poor at identifying underlying causality, and even poorer at treating it. I've found most medical doctors to be utterly useless in every facet, for everything. You could go in with a rash wanting to know what it is and get multiple different diagnosis. It's just how it is. Certainly get yourself to a nutritionist if you do nothing else, a consultation shouldn't cost more than £100 and the suggestions they offer are often invaluable. I have one and she is fantastic.
