The prevalence of very severe obesity has increased progressively and faster than other classes of obesity over the last years. It is unclear whether the prevalence of obesity-related complications and health risks increases progressively or reaches a plateau above a certain degree of obesity. The aim of our study was to investigate whether the severity of obesity was correlated with the prevalence of type 2 diabetes mellitus (T2DM), impaired fasting glucose, impaired glucose tolerance (IGT), metabolic syndrome (MS), and cardiovascular diseases (CVDs) in a large cohort of patients with different degrees of obesity. A cross-sectional study was conducted in 938 obese patients without a previous diagnosis of diabetes. Patients were assigned to different categories of obesity: mild-moderate obesity (BMI 30-39.9 kg/m(2)), morbid obesity (BMI 40-49.9 kg/m(2)), and super-obesity (SO, BMI ≥50 kg/m(2)). The prevalence of IGF, IGT, screen-detected T2DM, MS, and CVD was higher in SO patients than in the other groups. Interestingly, the association between SO and either MS or CVD was independent of glucose tolerance status, indicating that factors other than glucose metabolism also favor cardio-metabolic complications in obese patients. In patients without screen-detected T2DM (n = 807), insulin sensitivity and secretion OGTT-derived indexes indicated that SO patients had the worst glucose homeostasis relative to the other categories of obesity, which was indicated by the most reduced disposition index in these patients, a predictor of future T2DM. In conclusion, SO patients have an extremely high prevalence of glucose metabolism deterioration, and cardio-metabolic complications are more prevalent in these patients compared to less obese patients.