Classifying diabetes according to the new WHO clinical stages

To test the usefulness of the new WHO criteria for clinical staging of diabetes in the characterization of 1977 diabetic patients.

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).

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).

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.