Aims/Hypothesis: To test the usefulness of the new WHO criteria for clinical staging of diabetes in the characterization of 1977 diabetic patients. Methods: The following clinical stages were used: patients on diet and/or oral antidiabetic agents 2 years after diagnosis were considered as non-insulin requiring (NIR; n = 711) and patients who required insulin therapy after 1 year as insulin requiring for control (IRC; n = 543). Patients who because of deteriorating hyperglycemia within 1 year required insulin therapy were considered as insulin requiring for survival (IRS; n = 743). Results: The NIR patients had the highest age at onset (52 ± 12 years; mean ± SD), BMI (29.3 ± 5.2 kg/m²) and C-peptide concentrations (median 0.98 nmol/l; interquartile range 0.72–1.31 nmol/l) but the lowest frequency of GAD antibodies (5.5%) compared to the IRC and IRS groups. The IRC group had a high age at onset (49 ± 13 years), BMI (28.0 ± 4.8 kg/m²), frequency of GAD antibodies (16.8%), intermediate C-peptide concentrations (0.56 nmol/l, interquartile range 0.28–0.94), and the highest prevalence of nephropathy (31.5%) and neuropathy (68.1%). The IRS group had the lowest age at onset (23 ± 15 years), BMI (24.2 ± 3.4 kg/m²), C-peptide concentrations (0.05 nmol/l, interquartile range below detection limit 0.01) and highest frequency of GAD antibodies (44.5%). Retinopathy was more common in IRS than in IRC patients (62.1 vs. 43.9%; p < 0.001). Conclusions: The new WHO criteria seem to discriminate three distinct subgroups and thus provide a useful tool for clinical staging. The IRC patients seem to have a more severe disease than the IRS patients, which has not been clearly acknowledged in the etiological classification. However, because of the cross-sectional nature of these data, they need to be confirmed in a prospective study with defined cut-off limits for when insulin should be initiated.