[Association between sleep disorders and dawn phenomenon in patients with type 2 diabetes mellitus]

To explore the association between sleep disorders and dawn phenomenon in patients with type 2 diabetes mellitus (T2DM).

From July 2011 to July 2014 at Metabolic Disease Hospital, Tianjin Medical University, 316 T2DM patients on continuous glucose monitoring were divided into two groups according to the Pittsburgh Sleep Quality Index, i.e. those without sleep disorders (n = 186) and those with sleep disorders (n = 130). Biochemical parameters including hepatorenal functions, blood lipids, glycosylated hemoglobin (HbA1c) and fructosamine were detected. Oral glucose tolerance test, insulin releasing test and glucagon releasing test were performed to detect the inter-group differences of glucose concentration and α-cell and β-cell functions after fasting and glucose loading. And the correlation and regression analyses were performed between sleep disorders and other parameters.

The level of HbA1c, fructosamine, increment of fasting glucose and nocturnal nadir glucose, glucose increment before and after breakfast, 24 h mean glucose, fasting insulin, homeostasis model assessment of insulin resistance index (HOMA-IR) and area under curve of insulin were significantly higher in patients with sleep disorders than those without sleep disorders (8.2% ± 2.0% vs 7.4% ± 1.7%, (0.33 ± 0.10) vs (0.29 ± 0.07) mmol/L, (1.511 ± 0.294) vs (0.889 ± 0.233) mmol/L, (2.144 ± 0.400) vs (1.522 ± 0.378) mmol/L, (9.917 ± 1.800) vs (8.694 ± 1.622) mmol/L, (13.49 ± 4.68) vs (12.16 ± 4.56) mU/L, 4.98 ± 0.90 vs 3.82 ± 0.82, (8.47 ± 0.59) vs (8.25 ± 0.54), all P < 0.05). Insulin sensitivity index was lower in patients with sleep disorders than that in those without sleep disorders (-4.28 ± 0.62 vs -4.03 ± 0.52, P < 0.05). The level of glucagon at each timepoint and area-under-curve of glucagon were significantly higher in patients with sleep disorders than those without sleep disorders. The levels of 0, 30, 180 min glucagon/insulin ratio and glucagon/glucose ratio were significantly higher in patients with sleep disorders (all P < 0.05). Sleep disorder was positively correlated with HOMA-IR, glucagon/insulin ratio, increment of fasting glucose and nocturnal nadir glucose and dawn phenomenon (all P < 0.05). Yet there was a negative correlation with insulin sensitivity index (P < 0.05).

Sleep disorders are associated with dawn phenomenon. And improving sleep disorder helps to improve the dawn phenomenon and optimize overall glycemic control.