Please refer to this thread: What type of insulin should I ask for?
My history is similar to Ashley. She states: negative antibodies, lowish c-peptide, postprandial spikes.
2 years ago, I went to my GP with concerns of diabetes. Test results back then: Hba1c was 4.6%, fasting 3.9 mmol/l.
Begged for OGTT. Got it. While low carbing took it, result: 13.2 mmol/l at 2 hours. Came down on my own at 3 hours.
Referral to endo. Repeat HbA1c, fasting, fructosamine, antibodies. All normal. C-peptide 0.68 (below reference range, normal fasting, so he did not care about low c-peptide). While on low carb, do OGTT again. Failed at 14.2 mmol/l at 2 hours, coming down to 3.9 mmol/l at 3.5 hours. Diagnosis: diabetes unlikely. Eat normal diet.
Current period: 2019 June, c-peptide (1.0) bottom reference range. hba1c 4.9%, fasting between 5-5.6 mmol/l. Still low carb. Decided to start ramping up carbs in mid-December. Tried with 15g at a time. What I saw was frequent spikes to 8 mmol/l, which lasts for around 2.5 hours, then comes down to below 6 mmol/l at around 3 hours. Went to another endo a few days ago. She said my c-peptide is too low (I found multiple studies with normal people having c-peptides around 1.0-1.4 ng/ml on keto). I told her 2 years ago I failed OGTT. She said one needs to eat 200g of carbs a day for a week before OGTT to get accurate result. I told her about antibodies that were negative. Asked if I should repeat them, she said ‘not necessary’. Can antibodies appear from being absent? I have not noticed my BG control getting worse, still getting similar fastings, postprandials and low carb diet manages condition OK. It has been 2 years, surely if something was attacking pancreas, I would experience obvious issues?
But I still have low c-peptide and postprandial spikes so that is what she focused on. In the end, she said: eat 150g of carbs for 2 weeks, come in to repeat OGTT. Diagnosis: suspected MODY diabetes. Problem is, there is not a strong family history for it. I asked her if reference ranges for c-peptide are from people eating normal diet, she said “yes”. So … for all I know, my pancreas outputs enough insulin to keep me between where my body wants it: 5.0-5.6 mmol/l fasting.
I think my plan is this: get records from previous endo, see why he considers me not diabetic. If it is not convincing, I go repeat antibodies tests again and go from there. Any thoughts?