According to Medtronic, Auto Mode does not learn an individual’s time of day patterns or diurnal variations (i.e., dawn phenomenon) for the Medtronic MiniMed 670G.
Medtronic recommends the following for dawn phenomenon (word-for-word):
Morning highs: Assess for overnight / bedtime highs first, bedtime snack with inadequate or no bolus, morning caffeine. If issue is identified as dawn phenomenon, have patient test BG, take recommended correction dose and bolus for breakfast at least 15-20 minutes before eating. “SEe this medTronic document
The same would most likely apply for the Somogyi effect.
Basically for both the Somogyi effect and dawn phenomenon, your fasting BG reading are elevated in the morning due to peak production of the cortisol hormone (dawn phenomenon) or your liver compensating for low sugar at night (somogyi effect)