ESPE Abstracts

Introduction: Cardiovascular disease (CVD) is the major cause of morbidity and mortality in type 1 diabetes (T1D). Recent studies implicated deregulated phosphate homeostasis in the etiology of CVD. The objective of this study is to address the relationship between the phosphate-regulating hormone fibroblast growth factor 23 (FGF23) and cardiovascular risk factors in adults with and without type 1 diabetes (T1D).

Methods: A case-control study was conducted using data from patients with T1D and age- and sex matched controls without T1D from the Lifelines Cohort Study. Baseline demographic and clinical data, along with calcium-phosphate parameters including plasma C-terminal FGF23, were compared between T1D and controls and in subgroups, using the Mann-Whitney test.

Results: We included 302 adults in the T1D group and 302 adults in the control group. Mean age of males was 42yrs, of females 43yrs. Sex (50% female) was identical in both groups. Median HbA1c in the T1D group was 62mmol/l (7.8%). Median FGF23 in T1D patients was not significantly different from controls. Females with T1D had significantly higher FGF23 than males with T1D (83.3 vs 69.3U/ml, P=0.002), this was not observed in controls (75.6 vs 69.2U/ml, P=0.358). Serum phosphate, calcium, and alkaline phosphatase levels were higher and PTH levels were lower in T1D patients, compared to controls (all P<0.001), all within normal range. In the T1D group, FGF23 was positively correlated with serum phosphate (P<0.001), alkaline phosphatase (P=0.01) and calcium levels (P=0.001), these correlations were not observed in controls. In the T1D group the median FGF23 was significantly higher in current smokers (n=65, FGF23 84.9U/mL) than in non-smokers (n=235, FGF23 73.5U/ml, P<0.05). This difference was not present in the control group. Median FGF23 was not significantly different between subjects with or without hypertension, a decreased estimated glomerular filtration rate (eGFR, CKD-EPI formula) or an elevated urinary albumin/creatinine-ratio in both the T1D and control group. In our population there was no correlation between FGF23 and eGFR, with eGFR being in the normal range for nearly all subjects.

Conclusion: FGF23 in T1D patients was not significantly different from non-diabetes age- and sex matched controls. Serum calcium, phosphate and alkaline phosphatase levels were higher in T1D patients than in controls and were positively correlated to FGF23 in T1D patients. Current smokers with T1D had higher FGF23 levels than non-smokers with T1D. These findings may contribute to the increased risk of cardiovascular diseases in patients with T1D.