People with Type 1 Diabetes and Increased Hypoglycemia Frequency have a Higher Risk for Nocturnal Hypoglycemia During the Second Half of the Night

Based on the baseline data of a multi-center randomized CGM trial (HypoDE), we analyzed the glucose recordings of participants with an increased hypoglycemia frequency. All 126 participants had type 1 diabetes and were on an MDI insulin therapy (age 46.5±11.5 yrs., 36.5% female, HbA1c 7.5±1.0%, hypoglycemia unawareness score 5.0±1.1). Each participant used a blinded CGM system (DexCom Gen 4) for 28 days. The percentage of glucose readings ≤70 mg/dl over a 24h period (6 am to 10 am; 10 am to 2 pm, 2 pm to 6 pm, 6 pm to 10 pm, 10 pm to 2 am, and 2 am to 6 am) were analyzed. During the whole day, on average 7.6% of all 288 glucose readings per patients were ≤70 mg/dl. From morning to evening, 192 of ≤70 mg/dl readings were between 7.0% and 7.3%. In the early night, this percentage was lower than during the late night, in which the percentage of ≤70 mg/dl values rose to >10% (p<0.001). A similar pattern could be observed for mean glucose values during these intervals (figure).
Since study participants were at higher risk for hypoglycemia, they appear to have an elevated bedtime glucose in order to avoid nocturnal hypoglycemia.
This worked well during the first half of the night; however, during the second half of the night the hypoglycemia risk increased considerably.
A modification of nocturnal basal insulin supply should be considered in this high risk group.