Insulin Dependent T2DM or LADA, C-Peptide Levels and Medicare Coverage

After 30 years of T2DM onset, my recent fasting C-Peptide test is 0.3 ng/ml in the normal range of 0.9-7.1 ng/ml at BG of 165 mg/dl. I am asking myself whether I am LADA and meet the CMS criterion of C-peptide level (less than 110% of lower limit of normal range at a fasting BG ≀ 225 mg/dl) for Continuous Subcutaneous Insulin Infusion qualification. I will discuss with my ENDO in the upcoming appointment.

There are discussions of the C-peptide levels in several threads of this forum for meeting CMS criteria, say C-peptide level of 0.2 or 0.5, not sure about the unit of measurement. One paper concludes that β€œA lower c-peptide, specifically less than 0.2 nmol/l (or 0.6 ng/ml), can most likely predict requirement for insulin, but can values be used to predict likely time until insulin prescription? β€œ in the paper β€œ[A Practical Review of C-Peptide Testing in Diabetes, published online 2017 May 8, in Diabetes Therapy.”](http://A Practical Review of C-Peptide Testing in Diabetes, published online 2017 May 8, in Diabetes Therapy)

This paper also indicates that β€œC-peptide is a useful indicator of beta cell function, allowing discrimination between insulin-sufficient and insulin-deficient individuals with diabetes” and β€œLower c-peptide values have been shown to correspond with increased incidence of microvascular complications.”

In my numerous BG tests over the years, I notice that blood flowing into the meter sensor is much faster in the normal BG range of 80 to 110 mg/dl. When BG readings are much higher or lower, blood flowing into the meter sensor is much slower, i.e. higher viscosity or lower velocity. Do the low BGs reveal the increased incidence of microvascular complication as indicated in the paper?

Tandem Diabetes Care specialist explains the calculation of the absolute value of c-peptide test result β€œless than 110% of lower of normal range" to qualify for the insulin infusion pump under Medicare Plan B DME for Insulin Dependent T2D. In the above example, the normal range of C-peptide from this particular lab is 0.9-7.1 ng/ml. Therefore, the less than 110% level is 0.99 ng/ml (=1.1x0.9).

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