Spontaneous and transient predinner hyperglycemia in some patients with diabetes: Dusk phenomenon.

Blood glucose fluctuations have higher risk than absolute blood glucose level in diabetic chronic complications. At present, "dawn phenomenon" is well known by clinicians, but "dusk phenomenon" has not been recognized. This study explored the objective existence of "dusk phenomenon" (spontaneous and transient predinner hyperglycemia) and its clinical significance.The data of 54 patients with diabetes, who received routine insulin pump therapy between December 2010 and October 2012 in our hospital, were retrospectively analyzed. These patients included 4 patients with type 1 diabetes mellitus (DM) (T1DM) and 50 patients with type 2 DM (T2DM). According to the difference between predinner and postlunch blood glucose levels, the 50 patients with T2DM were divided into dusk phenomenon group (4 patients, all the differences ≥0 mmol/L during insulin pump therapy), nondusk phenomenon group (12 patients, all the differences <0 mmol/L during insulin pump therapy), and suspicious group (34 patients, the differences were uncertain during insulin pump therapy). In the 4 patients with T1DM of this study, the differences all were more than 0 mmol/L during insulin pump therapy. The changes in blood glucose levels were observed, and the correlations of blood glucose level with other factors were analyzed in T1DM and T2DM patients, respectively.In T1DM patients, blood glucose level was significantly higher in predinner than in prebreakfast and prelunch (all P < 0.01), and in postdinner 2 hour than in postlunch 2 hour (P = 0.021). The predinner blood level had no significant correlations with the blood glucose level at other time points and insulin dosages (all P > 0.05). In T2DM patients, the predinner blood glucose level was significantly higher in dusk phenomenon group than in suspicious group and nondusk phenomenon group (all P < 0.05). In dusk phenomenon group, the blood glucose level remained rising from predinner to prebed, and the predinner blood glucose level was only significantly correlated with postdinner 2-hour blood glucose level (P < 0.05).The "dusk phenomenon" (spontaneous and transient predinner hyperglycemia) is an objective existence in some patients with diabetes. The predinner hyperglycemia can affect blood glucose control between postdinner and prebed. Awareness of the "dusk phenomenon" has important clinical significance.