Anti GAD and C-Peptide Tests Inconclusive

I was first diagnosed as a Diabetic back in November 2017. My bloods were done and it took around 4 weeks for the tests to come back. They were inconclusive back then. So they took the results as they were and treated with background insulin (Tuojeo) and Metformin (500mg BD)

I was discharged from the ED and was given an appointment to attend 3 days later. After them seeing my Blood Sugar readings for the past 3 daya they decided to put me on NovoRapid with my meals. In the past few weeks the Diabetes Team have been trying to knuckle down on what type I am because if alternative treatments would work for me (other than insulin) then obviously it would be better but currently I am able to control my diabetes with insulin.

Due to my initial anti GAD tests being inconclusive they decided to repeat them. The tests showed the same result. So now I have been asked to make a very detailed record on my eating patterns along with carbs along with my how many units I take etc.

When I say my Anti GAD and my C-Peptide tests were inconclusive what I am saying is:

Anti GAD: Positive for T1
C-Peptide: Negative for T1

If anyone has heard of this before or has experienced something different or has any advise, please let me know. TIA

Contralto said:

What were your numbers for each test?

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14 for Anti GAD which is double normal range.

I believe the C-Peptide was in the 1200s.

barrym said:

I'm in the same boat. GAD test six years ago was inconclusive. After honeymoon period I went on to Lantus then Novorapid. If I had been positively a T1 what alternatives would there be?

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Exactly as you are now with your Lantus and NovoRapid together and that would be it.

catapillar said:

@LenCabe your GAD results were positive. You definitely have autoimmune type 1 diabetes. Your c-peptide tests were positive because you are honeymooning. The autoimmune kill off of the insulin producing beta cells isn't like flicking a switch, it takes time and in an older person in can take even longer. Often newly diagnosed type 1 adults have problems with their honeymoon period (while they have some residual insulin production) as taking insulin gives their beta cells a bit of a breather and they suddenly have a decent amount of endogenous insulin production happening, resulting in a lot of hypos.

Anyway, your results aren't inconclusive, GAD positive means definitively type 1. It's normal for a newly diagnosed type 1 to have positive cpeptide results because there will be residual insulin production for a few months or years after diagnosis.

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I think your explanation is what's exactly going on. I am just going off what I have been told by the Diabetic Nurse but just feel a little in the dark. The Diabetic Nurse said that this is something her and her colleagues had never seen before hence why they may feel an inconclusive result in summery of what is going on.

I appreciate the explanation. Would the fact that I am 18 be a factor in anything else relating?

catapillar said:

At 18 your immune system is going to be more efficient at killing off the beta cells than someone diagnosed in their 40s where they might be called LADA or 1.5 because then the honeymoon period can be long and occasionally strong enough to come of insulin all together for a short period. Was the DSN interpreting the results a paediatric diabetic nurse, because in children the immune system is efficient at wiping out the beta cells once it's decided they've gotta die, so a positive cpeptide test in a newly diagnosed type 1 child would be more unusual. But it's definitely common for adults, for example the transplant programme for pancreas or beta cell transplant requires you to have no c-peptide, type 1 adults wanting a transplant will get stuck off the list.

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I assume the clinic is for all ages but I do see more adults than children in the waiting room when going to appointments.

The clinic is regional and covers most of the county.

My current course of action is to record all insulin use and eating habits and then go to another appointment with 7 days worth of data as per the DNS. Hopefully all is more clear after that.