I know three possible factors that can keep your blood sugar levels higher in the morning – the waning insulin effect, the dawn phenomenon, and the Somogyi effect.
- Waning insulin effects. There is a possibility that your evening meals could cause your normal glucose levels to rise every morning, but the cause of the rise in glucose level in this situation may not be as a result of a small amount of insulin from your meal, prolonged effects of an insulin injection given the evening before the morning in question, or an inadequate amount of a pumped dose of basal insulin administered overnight. If an overnight basal rate of insulin or the evening dose of insulin is inadequate, it is likely that your blood sugar levels may increase during your sleep. Waning insulin increases your blood sugar at a more gradual pace than what happens in the dawn phenomenon or dawn effect.
- The dawn effect. The dawn phenomenon is nothing but the product of the generality of all the natural body changes that take place during your sleep cycle and it can be described in the following way: Between midnight and 3: 00 a.m. in the morning, your body has very little need of insulin. This is the period when your body enjoys the calmest sleep. During this period, any insulin taken the evening before will cause your blood sugar levels to experience a very sharp drop during this period. Then between the hours of 3:00 a.m. and 8:00 a.m., your body churns out stored glucose sugar in preparation for the new day which is about to break forth. Your body equally releases a certain amount of hormones to reduce your body's sensitivity to insulin. Every one of these effects take place the same time your bedtime insulin wears off. A combination of all these events is the sole reason why your blood sugar levels increases when you wake up in the morning.
- The Somogyi effects. Another possible cause of increase in the level of blood sugar in the morning is the Somogyi effect. This phenomenon was named after the medical practitioner who first wrote about it. Although the whole cascade of events that lead to high blood sugar in the morning is not any different from those of the dawn effect, the cause here can be said to be more man-made. In the Somogyi effect, the human blood sugar rises every morning as a result of very poor diabetes management. In one situation, your blood sugar levels may become too low during the night, and then your body gives out some important hormones to get the sugar levels high again. There are two reasons why this could happen-if you took very little snack before your bedtime or had too much insulin before bedtime. The other situation that can be responsible for the increase in blood sugar levels is when you take inadequate dose of long-acting insulin before your bedtime. If this is the case, you will often wake up with a higher blood sugar levels. You can see the link below on how you can handle such situations.
Source: http://www.webmd.com/diabetes/morning-high-blood-sugar-levels