A1C Creeping Up, C-Peptide Borderline — LADA Diabetes?
35M
5’8
143lbs
Non-Smoker
Beta Thalassemia Minor Trait (not full beta thalassemia)
Ferritin 29
Bilirubin 0.7
Hemoglobin currently 12.3
No autoimmune history or family history of T1
One grandma with T2
Concerned about possible LADA diabetes due to fasting c-peptide and A1C, but lots of confounders and not sure what to do next. I’ve tried to be detailed and thank you in advance for your time. Please forgive me if I’m coming across as a tourist in your forum, it’s not my intention.
A1C history:
5.2–5.3% (pre-2022)
April 2024: 5.4
April 2025: 5.6
April 2026: 5.7
Fasting Glucose History:
Historical range: 78–94 mg/dL
April 2025: 91
April 2026: 85
Other labs from April 2026:
Fasted for 13 hours
Fasting Insulin: 4.3 µIU/mL
C-Peptide: 0.72 ng/mL (lab reference range is .69 or higher)
Fructosamine: awaiting results
Triglycerides: 58 mg/dL
Additional Context:
Consume roughly 130-150g of carbs most days for the last 12 months.
For the 12 months I’ve also been intermittent fasting 16:8 protocol, fasting for 16 hours 5-6 days a week.
Intentionally lost about 15lbs as I was wanting to lean out for athletic and mobility reasons.
Doctor does not seem at all concerned with these labs but I am very concerned with the c-peptide and HbA1C creeping up.
He feels that the c-peptide and insulin being this low is not surprising given my glucose at the time. Also said if I had LADA there is no way my fasting would have been so stable over the last several years. I am just not convinced.
I understand thalassemia minor trait can impact A1C so I’m not as concerned with the specific number as I am with the trend. I have also read that dietary habits and fasting can drive c-peptide down into the lower ranges of normal in lean people.
While waiting for fructosamine I even bought my own finger stick monitor and tested some meals. I am at my wits end bc these numbers don’t seem to agree with the A1C and I’m also very nervous about the low insulin and c-peptide.
Meal testing with Contour Next One finger stick; just summarized instead of sharing every single time stamp. I tested at baseline and a minimum of 30/60/90/120/180 minutes later. For some meals, I tested even more often than that.
Fasting glucose ranged from 85–94 mg/dL across all days.
Postprandial glucose peaks were typically between 125–155 mg/dL, with one higher peak of 171 mg/dL following a ~50g carbohydrate meal with minimal fat or fiber.
Glucose generally peaked between 45–90 minutes, with some meals peaking closer to 120 minutes if they had lots of fat, protein and fiber.
Glucose levels consistently declined after peak and returned to near baseline (typically <100 mg/dL) within approximately 2–3 hours. The highest I had around 3 hrs was about 120mg/dl and that was a 60g carb meal with a ton of fiber and fat. It was near baseline about 20 mins after that.
Lower carbohydrate meals (<30g) produced smaller spikes, generally peaking below ~130 mg/dL. Some didn’t go higher than 115 mg/dl.
Higher carbohydrate meals (~50–60g) produced larger excursions, with peaks in the 140–170 mg/dL range.
And again all of this was finger stick testing where peaks tend to be a little higher.
What would you do? Any ideas?
My doctor is a good doctor but not an endo and I am prone to anxiety about these things. I had a very bad experience with a doctor misdiagnosing something as a child and it’s taken some therapy even to get where I am today.
Thank you in advance.