Nocturnal hypoglycaemia in type 1 diabetes--frequency and predictive factors.
BACKGROUND
Nocturnal hypoglycaemia (NH) remains a problem in type 1 diabetes and spontaneous asymptomatic NH may be a risk factor for sudden death ('Dead in Bed' syndrome).


OBJECTIVE
To explore whether any predictive relationship exists between the average or time-specific glycaemia and the occurrence of NH.


METHODS
Twenty-five healthy patients with type 1 diabetes underwent two separate overnight periods of continuous glucose monitoring (CGM) using a MMT-7002 Medtronic MiniMed System. There was a 6-week interval before the second monitoring period. CGM glucose levels recorded between 23:00 and 08:00 h defined the nocturnal period and recorded glucose monitoring levels <3.5 mmol/l for at least 10 min during this time-defined NH. A CGM recording at 23:00 h and 08:00 h were taken as the bedtime and fasting glucose levels, respectively.


RESULTS
The mean +/- SD age was 37 +/- 7 years and duration of diabetes 13 +/- 7 years; 16 (64%) were on long-acting analogue insulin. Forty-nine CGM data sets were recorded. Fourteen episodes of NH occurred in 12 patients (Group 1), 13 patients (Group 2) had no NH. Group 1 (NH) had a lower mean bedtime glucose recorded compared with Group 2 (7.7 +/- 4.3 vs. 11.4 +/- 4.0 mmol/l, P = 0.0035). Fasting glucose level was also lower in Group 1 following the occurrence of NH (P = 0.014). There was no difference in the type of insulin used between the two groups.


CONCLUSIONS
Our data show that in normal day to day settings, NH is common and that the bedtime glucose level is a significant predictive factor.
Woodward
A
A
Department of Diabetes and Endocrinology, University of Liverpool, Clinical Sciences Centre, Aintree University Hospital, L9 7AL, UK. a.woodward@liverpool.ac.uk
Weston
P
P
Casson
I F
IF
Gill
G V
GV
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000150:complications*; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D013997:Time Factors
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin