Aims/hypothesis  

Glucose fluctuations may help predict diabetic complications. We evaluated the relation between glucose variability and oxidative stress in patients with type 1 diabetes.

Methods  

Continuous glucose monitors were inserted subcutaneously in 25 patients. During the measurement, patients collected two 24 h urine samples, while 24 healthy controls collected one 24 h urine sample for determination of 15(S)-8-iso-prostaglandin \textF_2a ( \textPGF_2a ) {\text{F}}_{{2\alpha }} {\left( {{\text{PGF}}_{{2\alpha }} } \right)} using HPLC tandem mass spectrometry. Mean of the daily differences (MODD), mean amplitude of glycaemic excursions (MAGE) and continuous overlapping net glycaemic action calculated with n hour time-intervals (CONGA-n) were calculated as markers for glucose variability and correlation with 15( S ) - 8 - iso - \textPGF_2a 15{\left( S \right)} - 8 - iso - {\text{PGF}}_{{2\alpha }} excretion was calculated.

Results  

Median [interquartile range (IQR)] urinary 15( S ) - 8 - iso - \textPGF_2a 15{\left( S \right)} - 8 - iso - {\text{PGF}}_{{2\alpha }} was higher in patients than healthy controls: 161 (140–217) pg/mg creatinine vs 118 (101–146) pg/mg creatinine (p = 0.001). Median (IQR) MODD was 3.7 (3.2–5.0) mmol/l, MAGE 7.6 (6.4–9.0) mmol/l and CONGA-1 2.3 (2.1–2.8) mmol/l. Univariate regression did not reveal an association for MODD (r ² = 0.01), MAGE (0.08) or CONGA-1 (0.07) with 15( S ) - 8 - iso - \textPGF_2a 15{\left( S \right)} - 8 - iso - {\text{PGF}}_{{2\alpha }} excretion, nor was an association revealed when corrected for HbA_1c, age, sex and smoking. Spearman correlation coefficients (r) between 15( S ) - 8 - iso - \textPGF_2a 15{\left( S \right)} - 8 - iso - {\text{PGF}}_{{2\alpha }} excretion and MODD, MAGE and CONGA-1 were non-significant: −0.112, −0.381 and −0.177.

Conclusions/interpretation  

We report that there is no relationship between glucose variability and urinary 15( S ) - 8 - iso - \textPGF_2a 15{\left( S \right)} - 8 - iso - {\text{PGF}}_{{2\alpha }} . We also confirm that patients with type 1 diabetes have higher levels of urinary 15( S ) - 8 - iso - \textPGF_2a 15{\left( S \right)} - 8 - iso - {\text{PGF}}_{{2\alpha }} than healthy controls, suggesting that in addition to glucose variability, other factors favouring oxidative stress may exist. We did not see a relation between high glucose variability and elevated levels of oxidative stress in patients with type 1 diabetes.