Factors associated with high glucose variability in patients with type 1 diabetes

BACKGROUND: High glucose variability (GV) is recognized as a risk factor for vascular diabetic complications and hypoglycemia. Factors affecting GV in patients with diabetes needed to be clarified.AIM: To determine the factors associated with high GV in adult patients with type 1 diabetes.MATERIALS AND METHODS: We conducted a single center cross-sectional observational study. In-patients with type 1 diabetes aged 18 to 65 years on basal bolus insulin therapy were included. Day-time and nocturnal Coefficient of Variation (CV), Mean Amplitude of Glycemic Excursions (MAGE), Mean Absolute Glucose (MAG) were calculated from continuous glucose monitoring data. The values of CV, MAGE, MAG within the upper quartile were considered high.RESULTS: The study included 400 individuals, including 111 on continuous subcutaneous insulin infusion (CSII). Patients with high GV had lower fasting and postprandial C-peptide levels and higher insulin doses. According to ROC analysis, daily insulin dose >0.69 U/kg and estimated glomerular filtration rate (eGFR) ≥90.5 ml/min×1.73 m2 were associated with high nocturnal CV values. Dose of basal insulin >0.292 U/kg and bolus insulin >0.325 U/day were associated with nocturnal MAGE. Body mass index (BMI) ≤23.2 kg/m2, waist circumference ≤80.5 cm, daily insulin dose ≥0.69 U/kg, HbA1c ≥8.3%, eGFR ≥89.5 ml/ min×1.73m2 increased risk of high MAG at night. High day-time CV values were associated with daily insulin dose ≥0.675 U/kg and daily dose of BI ≥0.286 U/kg. The risk of high MAGE was increased with HbA1c ≥8.24% and basal insulin dose ≥0.286 U/kg. BMI ≤23.2 kg/m2, waist circumference ≤80.5 cm, daily insulin dose ≥0.69 U/kg, daily dose of bolus and basal insulin ≥0.325 and ≥0.29 U/kg respectively, and HbA1c ≥8.33% were the risk factors for high day-time MAG. Patients on CSII had lower MAGE (p<0.001) and MAG (p=0.008) compared to those on multiple daily injections.CONCLUSION: In type 1 diabetes, high GV is associated with undetectable residual insulin secretion, normal or reduced body weight, preserved kidney function, supraphysiological doses of insulin, and non-target HbA1c. Patients on CSII have a lower GV than those on multiple daily injections.