Elevated fasting plasma C-peptide occurs in non-diabetic individuals with fatty liver, irrespective of insulin resistance.
OBJECTIVE
Studies have pointed to insulin resistance as a pathogenic factor in fatty liver. Although pancreatic B-cell function is believed to be involved, its role is unclear. This study was undertaken to test whether fasting C-peptide, an index of fasting B-cell function, was related to intra-hepatic fat (IHF) content in non-diabetic humans.


METHODS
We assessed, retrospectively, fasting plasma C-peptide concentration in 31 patients with fatty liver and 62 individuals without fatty liver. The IHF content was measured by proton magnetic resonance spectroscopy ((1)H-MRS), while insulin sensitivity was estimated based on fasting plasma glucose and insulin with the homestasis model assessment (HOMA) 2 method.


RESULTS
Age, sex and body mass index (BMI) were not different between groups. Patients with fatty liver had higher fasting insulin (P < 0.01), C-peptide (P < 0.005) and lower insulin sensitivity (HOMA2-%S). Fasting insulin alone explained 14% of the IHF content variability (P < 0.001); inclusion of fasting C-peptide in multivariate regression explained up to 32% (P < 0.001). A subgroup analysis was performed by matching 1 : 1 for HOMA2-%S. These data were analysed by conditional logistic regression which showed that, when HOMA2-%S was matched between groups, fasting C-peptide remained the only significant predictor of fatty liver.


CONCLUSIONS
Non-diabetic individuals with fatty liver are characterized by increased fasting plasma C-peptide concentration, irrespective of their insulin resistant state.
Perseghin
G
G
Internal Medicine - Section of Nutrition/Metabolism, San Raffaele Scientific Institute, 20132, Milan, Italy. perseghin.gianluca@hsr.it
Caumo
A
A
Lattuada
G
G
De Cobelli
F
F
Ntali
G
G
Esposito
A
A
Belloni
E
E
Canu
T
T
Ragogna
F
F
Scifo
P
P
Del Maschio
A
A
Luzi
L
L
D000328:Adult; D001402:B-Lymphocytes / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism*; D002096:C-Peptide / Q000378:metabolism*; D005215:Fasting / Q000502:physiology; D005234:Fatty Liver / Q000378:metabolism*; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D012016:Reference Values; D012189:Retrospective Studies
D001786:Blood Glucose; D002096:C-Peptide