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Impact of the Dawn Phenomenon on Type 2 Diabetes Patients

Nov 22, 2013

About 50% of patients experience the dawn phenomenon…. 

This study included 248 patients with noninsulin-treated type 2 diabetes. Each of the patients were divided into three groups based on their current treatment. Those groups included diet alone (n = 53), insulin sensitizers (metformin or thiazolidinediones) alone (n = 82), and insulin secretagogues (sulfonylureas, glinides, DPP-4 inhibitors) alone or in combination with insulin sensitizers (n = 113). According to the study, the dawn phenomenon was quantified by its absolute increment from nocturnal nadir to prebreakfast value. Although when the treatment groups were compared there was no significant difference, the overall median magnitude of increase in the dawn glucose was 16 mg/dL. Then patients were divided into two paired subsets after they had been separated by the presence or absence of a dawn phenomenon based on a threshold of 20 mg/dL and matched for glucose nadir. When analyzed, both the HbA1c and 24-h mean glucose values were significantly higher in those who exhibited the dawn phenomenon in comparison to those who did not (P= 0.007 and P= 0.0009, respectively). Overall, the mean impact on HbA1c was 0.39% and 24-h mean glucose was 12.4 mg/dL. There was no significant difference seen between those on diet alone or those treated with oral hypoglycemic agents.


Based on the findings of this study, the researchers showed that the dawn phenomenon occurs in about 50% of patients and is present in those who are not taking any oral hypoglycemic agents. Additionally, the results indicate that the dawn phenomenon has a remnant impact on patients who are treated with current oral agents.

Practice Pearls:

  • Dawn phenomenon has an impact on patients with type 2 diabetes treated with diet alone or oral agents.
  • A rise in HbA1c of around 0.4% can occur in patients who experience the dawn phenomenon.
  • This phenomenon does not occur in persons without diabetes.

Diabetes Care, Published online October 2013