Your results are normal rather than just above T1. The Urine C-Pep/CR Ratio need to be below 0.2 nmol/mmol for type 1. Anything above is normal. They should be interpreted with blood sugar and not on their own also.
'The urinary C-peptide creatinine ratio is a practical non-invasive method to aid detection of absolute insulin deficiency, with a urinary C-peptide creatinine ratio
> 0.2 nmol/mmol being a reliable indicator of retained endogenous insulin secretion.'
https://pubmed.ncbi.nlm.nih.gov/23659458/#:~:text=The urinary C-peptide creatinine ratio is a practical non,of retained endogenous insulin secretion.
That paper you provided the link for is puzzling. It only used test subjects who are already using insulin treatment, so may not read across to T2D on orals. Not sure why they base predictions on this particular ratio. C-pep being low or close to zero is a marker for endogenous insulin deficiency, and will always dominate this ratio. i,e, 0 /n =0 regardless of n.
Several problems I see with this testing philosophy. Firstly, c-pep measures the insulin response to the meal. It is very dependant on there being trigger for the insulin response, and this requires carbohydrates in the diet. It therefore may not apply to those doing keto or LC diets, or intermittent fasting. Presumably, the follow-up test using the mixed meal is necessary to ensure that a standardised carb inclusive meal is used, but again it may be misled by long term LC use unless the person carbs up beforehand (as is required for the OGTT test)
We recently had another thread that ended up discussing creatinine as a biomarker for kidney failure, and it appears in this diagnostic tool as well. Several scientific papers and articles were posted in that thread that showed that creatinine is directly affected by several confounders
1) Only created directly by protein metabolism in the diet. No protein, no creatinine
2) significantly higher values if the protein is from animal sources, rather than plant-based.
3) affected by water intake - different results if the water is drunk to end a fast or dehydration, or if drunk with the meal.
4) the kidney test is taken at 2hrs, this ratio is at 90 mins
5) Level of exercise or exertion.
Creatinine is a byproduct of an amino acid called creatine which is essential for the creation and repair of muscle tissue. Creatinine is related to having excess to requirements load, and is probably not determined by the meal just eaten at 90 mins, but will reflect previous meals and activity.
Given the predominance of c-pep in the ratio at the trigger level, it is probably not going to have much effect but may skew borderline cases.
So I question why a carb-based value is being compared to a protein excess-based parameter since they are chalk and cheese. What is also not taken into account is that kidney failure reduces the excretion of creatinine into the urine, and this will have a significant impact on this ratio.
My take from the study report linked above is the time to start insulin treatment report and the BMI association report which are included in the washup at the end. So TOFI T2D beware! Your path to full progression would seem to be faster than normal T2D with extra padding. But there were only 9 subjects out of 191 in the cohort showing this, so based on a low sample size and possibly an unreliable observation.
