Gender, autoantibodies, and obesity in newly diagnosed diabetic patients aged 40-75 years

OBJECTIVE - To evaluate the frequency of autoimmune markers (islet cell antibodies [ICA] and glutamic acid decarboxylase antibodies [GADA]) and clinical features in newly diagnosed people with diabetes aged 40-75 years. RESEARCH DESIGN AND METHODS - Two hundred fifty-nine consecutive patients (aged 40-75 years) with newly suspected diabetes diagnosed during a 2-year period were studied. The diagnosis of newly discovered diabetes was confirmed in 203 patients. Gender, BMI, HbA(1c), fasting C-peptide, ICA, and GADA were evaluated. The frequency of obesity was estimated using two different sets of criteria: 1) National Diabetes Data Group (NDDG) criteria, and 2) criteria based on a Swedish reference population. RESULTS - The annual incidence of diabetes was 106 per 100,000 people. The incidence of diabetes in those patients who were 40-54 years old was significantly higher in men than in women (odds ratio: 2.16; P = 0.001). ICA were detected in 16 of 203 patients (8%), whereas 17 of 203 patients (8%) were GADA⁺; 10 of 203 (5%) patients were positive for both ICA and GADA. Among the 203 diabetic patients, 19 (9.4%) were classified as having IDDM, giving an IDDM incidence of 10 per 100,000 people aged 40-75 years. The frequency of obesity in NIDDM was high but varied with its definition; the frequency of obesity was highest (P < 0.001) when NDDG criteria, and not Swedish reference values, were used (57 of 75 [76%] vs. 40 of 75 [53%] for women and 66 of 109 [61%] vs. 45 of 109 [41%] for men). CONCLUSIONS - A striking male preponderance was found among incident cases of diabetes in people aged 40-54 years. Autoimmune markers were detected in 10% of incident cases of diabetes in people aged 40-75 years. Using a conservative estimation, as many as 10 of 100,000 middle-aged and elderly subjects developed IDDM. The frequency of obesity in NIDDM was high but this was also the case in the reference population.