Social consumption of alcohol in adolescents with Type 1 diabetes is associated with increased glucose lability, but not hypoglycaemia.

Aim: To determine the effects of social consumption of alcohol by diabetic adolescents on glycaemic control.

Methods: Fourteen (five male) patients aged > 16 years were recruited from the diabetes clinic at the Royal Children's Hospital. The continuous glucose monitoring system (CGMS) was attached at a weekend when alcohol consumption was planned for one night only. For each patient, the 12-h period from 18.00 h to 06.00 h for the night with alcohol consumption (study period) was compared with the same period with non-alcohol consumption (control period) either 24 h before or after the alcohol study night. Thus, each subject was his/her own control. Glycaemic outcomes calculated from continuous glucose monitoring included mean blood glucose (MBG), percentage of time spent at low glucose levels (CGMS < 4.0 mmol/l), normal glucose levels (CGMS 4.0-10.0 mmol/l) and high glucose levels (> 10.0 mmol/l) and continuous overall net glycaemic action (CONGA).

Results: The mean number of standard alcohol drinks consumed during the study period was 9.0 for males and 6.3 for females. There was no difference in percentage of time at high and normal glucose levels in the study and control periods. During the control period, there was a higher percentage of time with low glucose levels compared with the study period (P < 0.05). There was an increased level of glycaemic variation during the study time when compared with the control period.

Conclusions: In an uncontrolled, social context, moderately heavy alcohol consumption by adolescents with Type 1 diabetes appears to be associated with increased glycaemic variation, but not with low glucose levels.