Aim: To characterize the clinical phenotype of type 2 diabetes mellitus (T2DM) with respect to age, gender, and BMI. Method: Anonymized data of 120 183 people with T2DM from the German/Austrian multicenter Diabetes Patienten Verlaufsdokumentation database were analyzed based on chronological age or age at diagnosis (0-19, 20-39, 40-59, 60-79, and R80 years). Age, gender, and BMI comparisons with clinical phenotype were made using c 2 and Kruskal-Wallis tests (SAS V9.2). Results: Of all the patients, 51.3% were male, average age was 67.1G12.7 years, and average disease duration was 9.9G9.1 years. More girls than boys were diagnosed during adolescence and more men than women during adulthood (20-60 years). No gender differences existed when age at diagnosis was R60 years. Patients were obese on average (BMI: 30.5G6.1 kg/m 2 ) and had significantly higher BMI values than German population peers. The BMI gap was widest in the younger age categories and closed with increasing age. Adult women were significantly more obese than men. Obese patients more often had elevated HbA1c (R7.5%), hypertension or dyslipidemia (irrespective of age), microalbuminuria (adults), or retinopathy (elderly) than nonobese patients. More men than women (20-60 years) had hypertension, dyslipidemia, or microalbuminuria while more women than men (R60 years) had hypertension or dyslipidemia. Conclusion: During puberty, more girls than boys were diagnosed with T2DM while during adulthood males predominated. T2DM manifested at comparatively lower BMI in males, and younger patients were more obese at diagnosis. Age, gender, and BMI were also associated with poor metabolic control and cardiovascular disease comorbidities/complications.