medwireNews: Prepubertal children with type 1 diabetes have greater variability in their blood glucose levels than older children, research suggests.
Continuous glucose monitoring (CGM) over 4 weeks in 107 young people aged 8 to 17 years revealed greater glucose variability among the 26% of participants yet to go through puberty compared with the 62% who were pubertal and the 34% of postpubertal individuals, with this variability independent of glycated haemoglobin (HbA1c) levels.
Mean glucose variability differed significantly when measured according to standard deviation, with respective values of 86 versus 79 and 77 mg/dL (4.8 vs 4.4 and 4.3 mmol/L). There was also a trend towards greater variation when assessed using the coefficient of variation (CV), at a corresponding 43% compared with 41% and 40%.
While mean glucose levels dropped in all three groups overnight, this was greatest in the prepubescent group, who also showed the lowest nadir overnight and highest peaks in the morning and early evening.
The study participants, half of whom were female and 95% of whom were White, all had type 1 diabetes for at least a year (mean=6.3 years). Mean daily insulin dose was 0.9 units/kg and 88% of those studied received treatment through a pump.
CGM data collected over a 4-week period were used to calculate mean glucose values for each hour of the day. After this, HbA1c was measured, and was an average of 7.8% (62 mmol/mol) in the entire group, with 34% of participants achieving levels below 7.5% (<5.8 mmol/mol).
The researchers found that mean glucose variability assessed using the CV strongly correlated with time in the hypoglycaemic range of less than 70 mg/dL (3.9 mmol/L) in all groups.
Young people with high glycaemic variability, defined as a CV greater than 36%, spent approximately an hour a day in the hypoglycaemic range compared with approximately 15 minutes for those with low glycaemic variability, at a CV of 36% or less.
“Our findings show that [HbA1c] alone does not capture the full range of glycemia in youth with type 1 diabetes and highlight the added insight provided by CGM data in the management of type 1 diabetes”, report Lori Laffel and colleagues, from Joslin Diabetes Center in Boston, Massachusetts, USA, in Diabetes Care.
“In particular, assessment of glucose variability through the use of CV can be considered in clinical practice in an effort to reduce the risk of hypoglycemia in youth with type 1 diabetes.”
By Anita Chakraverty
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