• HbA1c [ Time Frame: 15 months ] [ Designated as safety issue: No ]
• Insulin Dose [ Time Frame: 15 months ] [ Designated as safety issue: No ]

The purpose of this study is to determine whether Diamyd (rhGAD65 formulated in alum) is effective in preserving the body's own insulin producing capacity in patients recently diagnosed with type 1 diabetes.

• Drug: rhGAD65
• Drug: Placebo

• Active Comparator: This arm will receive 2 subcutaneous injections with 20 µg Diamyd on Days 1 and 30, i.e., 1 prime and 1 booster dose, followed by 2 additional single doses with Diamyd 20 µg on Days 90 and 270.
• Active Comparator: This arm will receive 2 subcutaneous injections with 20 µg Diamyd on Days 1 and 30, i.e., 1 prime and 1 booster dose, followed by 2 additional single doses with placebo on Days 90 and 270.
• Placebo Comparator: This arm will receive 4 injections of placebo, 1 each on Days 1, 30, 90, and 270.

Main Inclusion Criteria:

• Male and female patients between 10 and 20 years of age
• Insulin dependent type 1 diabetes mellitus diagnosed within the previous 3 months at time of screening
• Fasting C-peptide level at time of screening above 0.1 nmol/L
• Elevated GAD65 antibodies (GADA) at time of screening

Main Exclusion Criteria:

• Treatment with immunosuppressants or any anti-diabetic medications other than insulin
• A history of certain diseases or conditions (e.g. anemia, HIV, hepatitis, epilepsy, head trauma, neurological diseases or cerebrovascular accident, alcohol or drug abuse etc)
• Treatment with any vaccine within 1 month prior to planned first Diamyd dose or planned treatment with vaccine up to 2 months after the last injection with Diamyd, excluding the influenza vaccine
• Participation in other clinical trials with a new chemical entity within the previous 3 months
• Pregnancy or planned pregnancy within 1 year after the last Diamyd dose
• Presence of associated serious disease or condition which in the opinion of the investigator makes the patient non-eligible for the study