I found a CMS Decision Memo that is lengthy and describes the background, history of Medicare coverage, and more. Under Decision Summary it states this:
"CMS has determined that the evidence is adequate to conclude that continuous subcutaneous insulin infusion (CSII) is reasonable and necessary for treatment of diabetic patients: 1) who either meet the updated fasting C-peptide testing requirement or are beta cell autoantibody positive; and 2) who satisfy the remaining criteria for insulin pump therapy detailed in the Medicare National Coverage Determinations Manual (Medicare NCD Manual 280.14, Section A.5).
CMS has determined that fasting C-peptide levels will only be considered valid when a concurrently obtained fasting glucose is ≤ 225 mg/dL. Insulinopenia is defined as a fasting C-peptide level that is less than or equal to 110 percent of the lower limit of normal of the laboratory’s measurement method. Alternatively, for patients with renal insufficiency and a creatinine clearance (actual or calculated from age, gender, weight and serum creatinine) ≤ 50 ml/minute, insulinopenia is defined as a fasting C-peptide level that is less than or equal to 200 percent of the lower limit of normal of the laboratory’s measurement method. Levels only need to be documented once in the medical records.
CMS will also continue to allow coverage of all other uses of CSII in accordance with the Category B IDE clinical trials regulation (42 CFR 405.201) or as a routine cost under the clinical trials policy (Medicare NCD Manual 310.1)."