As reported by Morse et al. (1), night-eating syndrome (NES) is likely to produce an adverse outcome in patients with type 2 diabetes. NES is defined as a circadian delay in daily food intake distinguished by evening hyperphagia (25% daily food intake consumed after the evening meal) and/or nighttime awakenings to eat at least three times per week (2). In addition to eating greater amounts of food in the evening hours, patients with NES often choose disproportionately large quantities of fat- and carbohydrate-rich foods at night (3–5). Here, we observed that a late dinner and a short interval between dinner and bedtime, which are characteristics different from those of NES, are likely to be associated with type 2 diabetes and/or a pre-diabetes stage in Japanese subjects.
In the first group, 77 Japanese subjects with type 2 diabetes who were treated with oral antidiabetes agents without insulin (40 men and 37 women, mean ± SE age 58 ± 2 years) and 77 subjects without diabetes and matched for age were assessed in a cross-sectional analysis. We investigated the interval between dinner and bedtime by asking the subjects about their lifestyle. The interval between dinner and bedtime in subjects with type 2 diabetes was significantly shorter than that in subjects without diabetes (2.5 ± 0.1 vs. 3.3 ± 0.2 h, respectively; P < 0.05). In addition, the interval between dinner and bedtime in obese subjects (BMI >25 kg/m2) was significantly shorter than that in nonobese subjects (2.8 ± 0.2 vs. 3.4 ± 0.1 h, respectively; P < 0.05).
In the second group, 45 Japanese subjects with suspected pre-diabetes (A1C >5.5% or fasting plasma glucose >126 mg/dl) not taking medications and healthy age-matched subjects were assessed in a cross-sectional analysis (24 men and 21 women, aged 58 ± 2 years). Intervals between dinner and bedtime in suspected pre-diabetes–stage subjects were significantly shorter than those in healthy subjects (2.9 ± 0.2 and 3.4 ± 0.1 h, respectively; P < 0.05). The length of the interval was not associated with binge eating or the characteristics of NES.
These findings suggest that the interval between dinner and bedtime is shorter in Japanese subjects with type 2 diabetes or in those in a pre-diabetes stage than in nondiabetic subjects. A lifestyle that includes shorter intervals between dinner and bedtime might be an important factor that can be distinguished from NES in producing adverse outcomes of type 2 diabetes and obesity.
