Nocturnal hypoglycemia

Connected notes
- Hypoglycemia in patients with diabetes mellitus
Q. What percentage of hypoglycemia observed in the DCCT trial was nocturnal?
- 43%
Q. What are the various types of brain waves?
Q. What happens to the brain waves during hypoglycemia in an awake state?
- there is a reduction in alpha waves but an increase in theta and delta waves
Q. What happens in hypoglycemia during sleep?
- In children- there are no changes in brain waves observed
- In adults- when glucose is <45 mg/dl
  - There is a reduction of alpha waves
  - Prominent changes in theta waves
Q. Does the brain have the same sensitivity to hypoglycemia during sleep, as when they are awake?
- yes
- The threshold for glucose values when brain waves changes occur suggests there is the same sensitivity for brain changes during sleep as it is during an awake state
- Hence brain retains inability to respond to hypoglycemia in sleep, atleast in adults
Q. But is the counter-regulatory response during sleep the same as during the awake state?
- No
- The counter-regulatory response to hypoglycemia is less profound during sleep than in an awake state
- The glucagon response is preserved in non-diabetics, but in certain patients with diabetes it is blunted (see below)
- The third line of defense, the sympathoadrenal response is reduced in people.
Q. Does the stage of the sleep also determine the response?
- Yes
- The counter-regulatory response is also dependent on the stage of the sleep cycle when hypoglycemia occurs.
Q. What is the clinical consequence on sleep quality in patients having nocturnal hypoglycemia?
- Adults with recurrent nocturnal hypoglycemia have poor sleep quality
Q. What percentage of nocturnal hypoglycemia are asymptomatic?
- A large proportion are asymptomatic
  - 50% of adults and 78% of children are asymptomatic
  - It may even be prolonged and last for as much as 6 hours
Q. What are the changes that occur to hepatic glucose production during sleep?
- During sleep hepatic glucose output reduces in response to reduce peripheral utilization of glucose
- this is mainly driven by continuous basal insulin secretion
Q. It is true that type 1 and type 2 diabetes with beta-cell failure have reduced counter-regulatory hormones also?
- Yes
- In type 1 diabetes and those with beta-cell failure in type 2 diabetes also have blunted glucagon response
- This per se does not produce hypoglycemia but reduces their capacity to respond to hypoglycemia in case it develops
Q. What are the Somogyi effect and the Dawn phenomenon?
Q. Does the Somogyi effect exist in reality?
- Experimental evidence does show the existence of the Somogyi effect
- However, even during the period of NPH insulin use, it was rare
- The use of modern basal insulin nearly makes the phenomenon non-existent
Q. What is a good reliable test for predicting the risk of nocturnal hypoglycemia?
- The bedtime glucose value is a strong predictor of nocturnal hypoglycemia
- Bedtime glucose associated with nocturnal hypoglycemia
  - <108 mg/dl in adults with type 1 diabetes
  - <130 mg/dl in children with type 1 diabetes
- #Pearl:
  - Bedtime glucose is a good predictor of hypoglycemia earlier in the night
  - Fasting glucose a good predictor of early morning hypoglycemia
    - FBS <99 mg/dl for a patient on basal-bolus insulin suggests early morning hypoglycemia may have occurred
Q. Which SMBG is useful for the diagnosis of nocturnal hypoglycemia?
- 3 am glucose reading
- Though this is impractical
- Hence CGM is useful for the diagnosis of nocturnal hypoglycemia
Q. Broadly, what are the symptoms of nocturnal hypoglycemia?
- Symptoms may be subtle and variable
  - Poor sleep quality
  - Vivid dreams and nightmares
  - Morning headache
  - Chronic fatigue
  - Mood changes
  - Night sweats and Wet bedsheets and bedclothes (because of sweat)
  - Enuresis (in children)
  - Restless behavior during sleep
Q. Can it lead to mortality?
- Yes
- It can potentially trigger arrhythmia
- The "Dead-in-the-bed" syndrome
- Use of alcohol also contributes to the same in patients with diabetes
Q. Can convulsions occur due to nocturnal hypoglycemia?
- Yes
Q. What are the long terms issues with nocturnal hypoglycemia?
- Cognitive impairment
- hypoglycemia unawareness
Q. Can bedtime snacks reduce the risk of nocturnal hypoglycemia?
- Yes
- However, short-acting carbohydrates are not ideal for this purpose- they still make the patient vulnerable to hypoglycemia early in the morning
- Uncooked cornstarch is ideal for such an action
- Adding acarbose before dinner is also a useful way of preventing nocturnal hypoglycemia in both type 1 and type 2 diabetes
Q. What are the other ways of preventing nocturnal hypoglycemia?
- 1. Using modern long-acting basal insulin analogs
  - Glargine U300
  - Insulin degludec
- 1. Using rapidly acting insulin analogs before dinner
- 1. Use of sensor-augmented insulin pumps
Q. Does giving glargine U100 in the morning reduce the risk of nocturnal hypoglycemia?
- Yes
- In some patients, this is seen
- This is probably because glargine U100 may not work for 24 hours in some patients- hence the effect of glargine wears off during nighttime
- However insulin glargine U300 solves this problem