Association between insulin-like growth factor 1 and pancreatic volume in type 1 and type 2 diabetes: cross-sectional study of a Japanese population

Although IGF-1 is known to promote organ growth, including exocrine pancreas, the association between plasma IGF-1 levels and pancreatic size remains unclear in diabetic patients. This cross-sectional study was designed to investigate the correlations among pancreatic volume (PV) based on computed tomography, IGF-1 levels, age- and sex-adjusted IGF-1 levels (IGF-1 Z-score), and C-peptide levels in patients with type 1 diabetes (T1D) (n = 51) and type 2 diabetes (T2D) (n = 104) in a Japanese population. PV was significantly correlated with body weight (BW) in both types of diabetes. PV adjusted for BW (PV/BW), IGF-1 Z-score and C-peptide levels were significantly lower in patients with T1D than T2D. There was a significant positive correlation between C-peptide levels and PV/BW in both subtypes of diabetes. IGF-1 Z-scores were significantly correlated with PV/BW in patients with T1D (r = 0.37, P = 0.007), but not T2D. Although IGF-1 Z-scores were not correlated with age, age of disease onset, disease duration, HbA1c, or C-peptide levels in both types of diabetes, a multivariable liner regression analysis revealed that IGF-1 Z-score and C-peptide levels were independent correlates of PV/BW in T1D patients, while C-peptide levels were a sole correlate in T2D. Decreased IGF-1 levels might be one causal factor for smaller pancreas in patients with T1D. •IGF-1 is known to promote organ growth.•Pancreatic volume was lower in T1D than T2D.•IGF-1 Z-score was correlated with pancreatic volume in T1D, but not T2D.•Decreased IGF-1 levels might be one causal factor for smaller pancreas in T1D.