Magnitude of the Dawn Phenomenon and Its Impact on the Overall Glucose Exposure in Type 2 Diabetes Is this of concern?

OBJECTIVETo assess the magnitude of the dawn phenomenon and its impact on the total glucose exposure in type 2 diabetes.RESEARCH DESIGN AND METHODSA total of 248 noninsulin-treated persons with type 2 diabetes who underwent continuous glucose monitoring were divided into three groups selected by treatments: diet alone (n = 53); insulin sensitizers alone (n = 82); and insulin secretagogues alone or in combination with insulin sensitizers (n = 113). The dawn phenomenon ( glucose, mg/dL) was quantified by its absolute increment from nocturnal nadir to prebreakfast value. The participants were secondarily divided into two paired subsets after they had been separated by the presence/absence of a dawn phenomenon based on a threshold of 20 mg/dL and matched for glucose nadir. The impact of the dawn phenomenon was assessed on HbA(1c) and 24-h mean glucose.RESULTSThe median of glucose (interquartile range) was 16.0 (0-31.5 mg/dL) in the 248 subjects, and no differences were observed across groups selected by HbA(1c) or treatments. In the overall population, the mean impacts on HbA(1c) and 24-h mean glucose were 4.3 1.3 mmol/mol (0.39 +/- 0.12%) and 12.4 +/- 2.4 mg/dL, respectively. The mean impact on 24-h mean glucose was not statistically different between those on diet alone (16.7 +/- 5.9 mg/dL) compared with the two subsets treated with oral hypoglycemic agents (11.2 +/- 5.3 and 8.5 +/- 7.5 mg/dL).CONCLUSIONSThe impact of the dawn phenomenon on overall glycemic control in type 2 diabetes, as depicted by the HbA(1c) level, was approximate to 0.4% and not eliminated by any of the currently available armamentarium of oral antidiabetes agents.