Objective: The aim of this study was to explore the associations between inadequate glycemic control of diabetes and psychological, anthropometric, and lifestyle variables in a population-based cohort of type 1 diabetes patients. Design: Cross-sectional study. Methods: In this study, 292 patients with type 1 diabetes, aged 18-59 years, participated. Psychological data were assessed by self-report instruments: Hospital Anxiety and Depression Scale and Toronto Alexithymia Scale-20. Anthropometrics, blood analyses, data from medical records, and data from the Swedish National Diabetes Registry were collected. Results: Self-reported depression (adjusted odds ratio (AOR) 4.8), obesity (AOR 4.3), and smoking (AOR 3.0) were independently associated with inadequate glycemic control of diabetes (HbA1cO8.6%). Gender-stratified analyses showed that self-reported depression (AOR 19.8) and obesity (AOR 7.0) in women and smoking in men (AOR 4.2) were associated with HbA1cO8.6%. Alexithymia, antidepressant medication, and physical inactivity were associated with HbA1cO8.6% only in bivariate analyses. Alexithymia, self-rated anxiety, physical inactivity, and absence of abdominal obesity were associated with self-reported depression. Conclusions: Depression was the only psychological factor independently associated with HbA1cO 8.6%. The association was of comparable importance as obesity and smoking, well-known risk factors for inadequate glycemic control and diabetes complications. The association between depression and HbA1cO8.6% was particularly strong for women. Alexithymia, which is a relatively stable personality trait, was associated with depression. In the future care of patients with diabetes, psychological aspects should be considered alongside anthropometrics and lifestyle factors in order to achieve the goals for HbA1c.