Below a specific threshold, FCP exerts a protective effect, but above that threshold the protective effect becomes uncertain.

Measurement of plasma glucose, insulin ... 1.7 mmol/l (normal range 3.9–6.9 mmol/l), insulin levels of 2.7 mIU/l (normal range <3.0 mIU/l in the presence of hypoglycemia), C-peptide ...

Patients were randomly assigned to receive daily subcutaneous injections of replacement-dose C peptide (1.5 mg), high-dose C peptide ... participants compared with normal values.