What happens to blood glucose overnight - Dr Pratik ... - Dafne

What happens to
blood glucose
overnight?
Dr Pratik Choudhary
Senior Lecturer and Consultant in Diabetes

Frequency of nocturnal
hypoglycaemia
UK Hypoglycaemia study ; Diabetologia, 2007
% patients with at least 1 noct
hypo over 5 days of CGM

Effect of nocturnal
hypoglycaemia
• Fear of hypos
• 55% of SH in DCCT were nocturnal
• 18% absentee-ism the day after
nocturnal hypoglycaemia
• Decreased work performance following
day
• Reduced consolidation of memory
overnight

Overnight balance
Glucago
n
Insulin
Alcohol
Exercise
Inadequate basal
Illness

Fasting
hyperglycaemia
Glucose ( mmol/l)
Hypoglycaemia
Time

The dawn
phenomenon
• > 10,000 patients surveyed
• Marked basal rise between
0400 - 0800 in post pubertal
patients.
• Seen in 20-30% T1 pts
• Due to a rise in frequency
and amplitude of growth
hormone pulses through the
night
• Possible contribution from
increase in cortisol in the
morning
Bachran et al; Pediatric Diabetes 2012: 13: 1–5

Dawn Or Somogyi??
Breakfas
t

• 5 pts with “unmanageable”
diabetes
• Treated with 3 -4 times /
day soluble insulin
• Recurrent DKA and SH
• Insulin dose reduces from
60-70 units down to 18-30
units
• 2 further pts, one who
came off insulin
“Hypoglycaemia begets
hyperglycaemia”
American Journal of Medicine; 1959

Reduced insulin levels as long acting insulin
ran out were associated with high blood
glucose levels

NEJM;
1998

T1DM
Normal
Diabetes, 2003

Hoi-Hansen et al; Diabetologia
(2005)

Much of the variability in
fasting BG comes form the
night before

Data from Sheffield
• The data is unpublished so unfortunately I
cannot provide the visual graphs
• However:
• If fasting glucose is < 5 80% chance
that the patient had a nocturnal hypo
• There were NO instances of overnight
hypoglycaemia that resulted in a high
fasting glucose in over 100 nights

Contd….
• Night time hypos were spread equally
through the night
• 30% of patients had well controlled overnight
glucose with high fasting glucose
Dawn phenomenon
• Bedtime capillary glucose had NO predictive
value for overnight hypoglycaemia

Much of the variability in
fasting BG comes form the
night before

Summary
• Nocturnal hypoglycaemia is common
• Low fasting glucose is an important marker
of overnight hypoglycaemia
• Very little evidence to support Somogyi
effect.
• 3 am test / CGM can be used to identify
nocturnal hypos / Dawn phenomenon
• Much of the variability in fasting glucose
comes from the evening meal..

Thank you...

Relationship of fasting
and nadir glucose