After 6 years of intraperitoneal insulin administration IGF-I concentrations in T1DM patients are at low-normal level

• This study describes the effect of continuous intraperitoneal insulin infusion (CIPII) on IGF1 concentrations in type 1 diabetes mellitus.
• After 6 years of CIPII, IGF1 concentrations increased to a higher level than during prior subcutaneous insulin treatment.
• These IGF1 levels are in the lower normal range compared to a non-diabetes reference population.
• This study suggests that long-term intraperitoneal insulin administration influences the IGF system in T1DM.

ObjectiveLow concentrations of insulin-like growth factor-I (IGFI) have been reported in type 1 diabetes mellitus (T1DM), suggested to be due to low insulin concentrations in the portal vein. The aim was to describe the long-term course of IGFI concentrations among T1DM subjects treated with continuous intraperitoneal (IP) insulin infusion (CIPII).DesignNineteen patients that participated in a randomized cross-over trial comparing CIPII and subcutaneous (SC) insulin therapy in 2006 were followed until 2012. IGF-I measurements were performed at the start of the 2006 study, after the 6 month SC- and CIPII treatment phase in 2006 and during CIPII therapy in 2012. Z-scores were calculated to compare the IGF-I concentrations with age-specific normative range values of a non-DM reference population.ResultsIn 2012, IGF-I Z-scores (− 0.7; 95% confidence interval − 1.3, − 0.2) were significantly higher than at the start of the 2006 study (− 2.5; − 3.3, − 1.8), the end of the SC (− 2.0; − 2.6, − 1.5) and CIPII (− 1.6; − 2.1, − 1.0) treatment phase with a mean difference of: 1.8 (0.9, 2.7), 1.3 (0.5, 2.1) and 0.8 (0.1, 1.6), respectively.ConclusionAfter 6 years of treatment with CIPII, IGF-I concentrations among T1DM patients increased to a level that is higher than during prior SC insulin treatment and is in the lower normal range compared to a non-DM reference population. The results of this study suggest that long-term IP insulin administration influences the IGF system in T1DM.