| I've been wondering about C-peptide in Type 1 in general... It does definitely prove that no natural insulin is present. But that does not necessarily mean that:
a) The beta cells are dead - they could be malfunctioning or unresponsive, much like a broken thermostat;
b) That beta cells are even malfunctioning - it could be that the insulin they produce is immediately recognized as a foreign body (for example due to a fault in the immune system) and destroyed.
Hopefully someone with a better knowledge of chemistry can clarify this, but I think there's still no method to prove any of the above for certain. | 
