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

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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• The data is unpublished so unfortunately I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

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