Type 2 Diabetes: Also a “Clock Matter”?

Background: We investigated whether chronotype is associated with glycemic control, antidiabetic treatment, and risk of developing complications in patients with type 2 diabetes (T2DM). Methods: The diabetologists filled out an online questionnaire on the Google Form platform to collect the following parameters of subjects with T2DM: body mass index (BMI), fasting plasma glucose (FPG), glycosylated hemoglobin (HbA1c), diabetes history, antidiabetic treatment, diabetic complications, and chronotype categories. Results: We enrolled 106 subjects with T2DM (M/F: 58/48; age: 63.3 ± 10.4 years; BMI: 28.8 ± 4.9 kg/m2). Thirty-five point eight% of the subjects showed a morning chronotype (MC), 47.2% an intermediate chronotype (IC), and 17% an evening chronotype (EC). EC subjects reported significantly higher HbA1c (p < 0.001) and FPG (p = 0.004) values, and higher prevalence of cardiovascular complications (CVC) (p = 0.028) and of subjects taking basal (p < 0.001) and rapid insulin (p = 0.01) compared to MC subjects. EC subjects reported significantly higher HbA1c (p < 0.001) and FPG (p = 0.015) than IC subjects. An inverse association was found between chronotype score, HbA1c (r = -0.459; p < 0.001), and FPG (r = -0.269; p = 0.05), remaining significant also after adjustment for BMI, age, and disease duration. Conclusions: EC is associated with higher prevalence of CVC and poorer glycemic control independently of BMI and disease duration in subjects with T2DM.