It is nocturnal glycemia caused by decreased effectiveness of insulin and overnight growth hormone release. Therefore, it causes early morning hyperglycemia.
Treat it by moving night-time insulin dose as close as possible to bedtime.
Nocturnal glycemia: It is normal but due to decreased insulin and increased GH release, early morning hyperglycemia occurs.
It is nocturnal hypoglycemia which leads to activation of counter-regulatory hormones such as cortisol, glucagon, epinephrine, norepinephrine and as such, results in early morning hyperglycemia.
Treat this by decreasing night-time insulin dose.
Nocturnal glycemia in Somogyi: It is low, which then leads to rebound hyperglycemia in early morning.
How to diagnose whether the early morning hyperglycemia in patient is due to Dawn Phenomenon or Somogyi Effect?
Both Dawn and Somogyi have early morning hyperglycemia. To distinguish between the two, decrease the insulin dosage at night. It is crucial not to increase insulin dose since this can result in coma if the patient has Somogyi effect.
Two possible outcomes:
1. If early morning hyperglycemia persists, it is Dawn phenomenon.
2. If early morning blood glucose is normal or decreased, it is Somogyi effect.
Debate regarding Somogyi credibility continues whether Somogyi effect to hypoglycemia is due to nocturnal hypoglycemia or not. In fact, hyperglycemia due to Somogyi effect can actually be due to an insulin-induced insulin resistance1.
1. Shanik MH, Xu Y, Skrha J, et al. Insulin resistance and hyperinsulinemia: is hyperinsulinemia the cart or the horse?. Diabetes Care. Feb 2008;31 Suppl 2:S262-8.