APOB and type 2 diabetes mellitus: In well‐controlled type 2 diabetic patients, serum C‐peptide levels have earlier been reported to significantly correlate with BMI (r = 0.21), HDL‐c (r = −0.22), non‐HDL‐c (r = 0.23), triglycerides (r = 0.39), apoB (r = 0.29), and systolic and diastolic blood pressure (Relimpio et al., 1997).