Hyperglycemia in the morning R73.9

The Somogyi effect was first described by Michael Somogyi in 1959 (Somogyi 1959).

In 1981, Schmidt et al. described the passive insulin resistance that leads to morning hyperglycemia as the so-called Dawn phenomenon. Campbell et al. proved in 1985 that this form of hyperglycaemia is due to a nocturnal secretion of growth hormones (Hürter 1997).

Hyperglycemia in the morning, fasting (by definition a blood glucose of > 125 mg / dl [Herold 2020]) is an elevated blood glucose level triggered by various causes.

The dawn phenomenon occurs particularly frequently in type 1 DM (Herold 2020) and in children and adolescents with pronounced diurnal rhythms (Hien 2007). The prevalence is estimated to be > 50 % for type 1 and type 2 DM (O'Neal 2021).

The Somogyi effect is found only very rarely (Howorka1988). Mostly children and adolescents with a pronounced hormonal diurnal rhythm are affected (Hien 2007).

The causes of morning hyperglycemia may be:

• 1. too short duration of action of the single morning administration of a delay insulin:

This causes nocturnal and especially morning hyperglycaemia (Herold 2020).

• 2. so-called Dawn phenomenon:

In the Dawn phenomenon, increased secretion of the growth hormone (GH) leads to an increased insulin requirement in the second half of the night (Herold 2020). There is no preceding hypoglycemia(Hien 2007). For more details see Dawn phenomenon.

• 3. The so-called Somogyi effect:

In this case, an excessively high evening insulin dose triggers nocturnal hypoglycaemia, which can then lead to reactive morning hyperglycaemia (Herold 2020). For more details, see Somogyi effect.

Both the Somogyi effect and the Dawn phenomenon can occur on different days in the same patient (Kolossa 2014).

In patients without diabetes mellitus, plasma insulin and blood glucose levels remain constant overnight. Only shortly before dawn is there a small increase in insulin secretion, which serves to suppress hepatic glucose production and prevent hyperglycemia (O'Neal 2021).

In the Dawn phenomenon, the nocturnal release of growth hormones decreases the excretion of nitrogen and promotes the uptake of amino acids into the cell. Growth hormones act synergistically with insulin - with regard to amino acid metabolism - and inhibit glucose uptake in the periphery (Siegenthaler 2006).

In the Somogyi effect, hypoglycemia in the context of a hormonal counter-reaction leads to a rise in blood glucose and thus also to insulin resistance (Mehnert 2003).

A moderate increase in blood glucose, as occurs in both the Dawn phenomenon and the Somogyi effect, does not usually cause any symptoms.

If, in addition to the morning hyperglycaemia, headaches, fatigue (Reinhardt 2004) and night sweats are also present, a Somogyi effect is the most likely differential diagnosis (Wehling 2006).

The diagnosis of morning hyperglycaemia consists of nocturnal blood glucose checks.

If the BG is high both at night and in the morning, this is most likely a dawn phenomenon (Reinhardt 2004). In the case of the dawn phenomenon, therefore, BG checks should be carried out at 10 p.m. / 2 a.m. / 4 a.m. (Herold 2020). For more details see Dawn phenomenon.

In the case of morning hyperglycaemia triggered by the Somogyi effect, these checks are recommended between 3 - 4 h (Herold 2020), as the greatest insulin effectiveness is between 0.00 h and 3.00 h (Hien 2007).

In the Somogyi effect, BG can be low at night and elevated in the morning (Reinhardt 2004), but much more often BG is low or normal in the morning. For more details see Somogyi effect.

CGM

The Dawn phenomenon can be masked by a Somogyi effect. Continuous glucose monitoring (CGM) should be used for further differentiation (Kolossa 2014).

In the Dawn phenomenon, ketone bodies are typically not found in morning urine (Furger 2003). In the Somogyi effect, however, they are found in the (glucose-free) morning urine (Hien 2007).

In epidemiological analyses, a 1% increase in HbA1c level was associated with a 15%-20% higher risk of cardiovascular complications.

In a study by Swedish researchers, a reduction in cardiovascular mortality of up to 45% was shown for a 0.8% decrease in HbA1c (O'Neal 2021).

• To 1. morning single dose of insulin:

Here, in addition to the morning insulin administration, a further evening insulin administration should take place in the ratio morning / evening: 2 - 3 to 1 (Herold 2020).

• 2. Dawn phenomenon:

The evening insulin dose with intermediate or long-acting insulin must be adjusted.

Alternatively, an insulin pump can be used, which should then be adjusted to an increased basal rate of insulin in the early morning hours (Herold 2020).

For more details, see Dawn phenomenon.

• To 3. Somogyi effect: The patient should not have a BG < 120 mg / dl before going to bed. If this is the case, it is recommended to take 2 - 3 BE. To avoid further occurrences of this kind, the evening dose of insulin should be reduced (Herold 2020). For more details see Somogyi effect.

It is important for the further prognosis of the diabetic with regard to the long-term consequences,

to achieve an optimal blood glucose level already in the early phase of the disease. If oral antidiabetics are not sufficient to prevent a dawn phenomenon, insulin should be switched to at an early stage. In addition, the recognition of a Dawn phenomenon is important to prevent increasing insulin resistance (O'Neal 2021).

The implantation of an insulin pump in childhood and adolescence is carried out in up to 48.8% to prevent the Dawn phenomenon (Kapellen 2006).

Recent studies conducted at Washington University School of Medicine suggest that diabetics with nocturnal hypoglycemias have hypo- rather than hyperglycemia in the morning. Nocturnal hypoglycemias also did not lead to hyperglycemia the following day in this study.

No correlation was found between elevated glucose levels and counter-regulatory hormones such as epinephrine, cortisol, glucagon, and growth hormones.

This would disprove the Somogyi effect (Reyhanoglu 2021).

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