CLAIMS 1. Use of an IL-21 antagonist for the manufacture of a medicament for the treatment of latent autoimmune diabetes in adults. 2. Use of an IL-21 antagonist for the manufacture of a medicament for prolonging the remission phase in patients with newly diagnosed type 1 diabetes. 3. Use of an IL-21 antagonist for the manufacture of a medicament for reducing the secondary failure rate of treatment with orally active hypoglycaemic agents and/or postponing the need for insulin therapy in islet cell antibody (ICA), insulin antibody-, heat shock protein (hsp) 60 antibody- and/or GAD antibody-positive patients with type 2 diabetes; 4. A pharmaceutical composition comprising an IL-21 antagonist in combination with another agent that suppress immune responses and/or promotes the generation of regulatory immune responses. 5. The use of an IL-21 antagonist for the manufacture of a medicament for the treatment of autoimmune diseases administered in combination with another agent that suppress immune responses and/or promotes the generation of regulatory immune responses 6. The use according to claim 5 wherein the autoimmune diseases are Type 1 Diabetes and LADA. 7. The use according to claim 5 wherein the compounds that suppress immune responses and/or promote regulatory immune responses are CD3 antagonists, hereunder OKT3, CD25 antagonists, CTLA-4 agonists, IL-2 antagonists, IL-2R antagonists, thiazolidin-diones (TZDs). 8. The use of an IL-21 antagonist for the manufacture of a medicament for the treatment of autoimmune diseases including T1D and LADA administered in combination with one or more agents that stimulates the regeneration or neoformation of β-cells, 9. The use according to claim 8 wherein the compounds that promote regeneration and/or neoformation of β-cells are selected from gastrin, gastrin analogues, epidermal growth factor (EGF), EGF-R agonists, fibroblast growth factor (FGF), FGF-R agonists, Keratinocyte growth factor, growth hormone (GH), Ghrelin, glucagon-like peptide (GLP)-1, GLP-1 analogues, hereunder Liraglutide; 10. The use of an? One or more? antagonist of IL-21 for the manufacture of a medicament for the treatment of complications and disorders resulting from or associated with obesity administered together with one or more antidiabetics, antiobesity agents, antihypertensive agents, and/or agents for the treatment of complications resulting from or associated with diabetes. 11. A pharmaceutical composition comprising an antagonist of IL-21 together with one or more compounds that suppress immune responses and/or promote regulatory immune responses. 12. A pharmaceutical composition comprising an antagonist of IL-21 together with one or more agents that stimulate the regeneration or neoformation of β-cells. 13. A pharmaceutical composition comprising an antagonist of IL-21 together with antidiabetics, antiobesity agents, antihypertensive agents, and/or agents for the treatment of complications resulting from or associated with diabetes. 14. A method for the treatment of latent autoimmune diabetes in the adults by administering an effective amount of an antagonist of IL-21; 15. A method for prolonging the remission phase in patients with newly diagnosed type 1 diabetes by administering an effective amount of an antagonist of IL-21; 16. A method for reducing the secondary failure rate of treatment with orally active hypoglycaemic agents and/or postponing the need for insulin therapy in islet cell antibody (ICA), insulin antibody, heat shock protein (hsp) 60 antibody and/or GAD antibody positive patients with type 2 diabetes by administering an effective amount of an antagonist of IL-21.CLAIMS 1. Use of an IL-21 antagonist for the manufacture of a medicament for the treatment of latent autoimmune diabetes in adults. Use of an IL-21 antagonist for the manufacture of a medicament for prolonging the remission phase in patients with newly diagnosed type 1 diabetes. Use of an IL-21 antagonist for the manufacture of a medicament for reducing the secondary failure rate of treatment with orally active hypoglycaemic agents and / or postponing the need for insulin therapy in islet cell antibody (ICA), insulin antibody-, heat shock protein (hsp) 60 antibody- and / or GAD antibody-positive patients with type 2 diabetes; A pharmaceutical composition comprising an IL-21 antagonist in combination with another agent that suppresses immune responses and / or promotes the generation of regulatory immune responses. 5. The use of an IL-21 antagonist for the manufacture of a medicament for the treatment of autoimmune diseases administered in combination with another agent that suppresses immune responses and / or promotes the generation of regulatory immune responses 6. The use according to claim 5 where the autoimmune diseases are Type 1 Diabetes and LADA. The use according to claim 5 wherein the compounds that suppress immune responses and / or promote regulatory immune responses are CD3 antagonists, hereunder OKT3, CD25 antagonists, CTLA-4 agonists, IL-2 antagonists, IL-2R antagonists, thiazolidin-diones (TZDs). 8. The use of an IL-21 antagonist for the manufacture of a medicament for the treatment of autoimmune diseases including T1D and LADA administered in combination with one or more agents that stimulates the regeneration or neoformation of β-cells, 9. The use according to claim 8 wherein the compounds that promote regeneration and / or neoformation of β-cells are selected from gastrin, gastrin analogues, epidermal growth factor (EGF), EGF-R agonists, fibroblast growth factor (FGF), FGF-R agonists, Keratinocyte growth factor, growth hormone (GH), Ghrelin, glucagon-like peptide (GLP) -1, GLP-1 analogues, including Liraglutide; 10. The use of an? One or more? antagonist of IL-21 for the manufacture of a medicament for the treatment of complications and disorders resulting from or associated with obesity administered together with one or more antidiabetics, antiobesity agents, antihypertensive agents, and / or agents for the treatment of complications resulting from or associated with diabetes. 11. A pharmaceutical composition comprising an antagonist of IL-21 together with one or more compounds that suppress immune responses and / or promote regulatory immune responses. 12. A pharmaceutical composition comprising an antagonist of IL-21 together with one or more agents that stimulate the regeneration or neoformation of β-cells. 13. A pharmaceutical composition comprising an antagonist of IL-21 together with antidiabetics, antiobesity agents, antihypertensive agents, and / or agents for the treatment of complications resulting from or associated with diabetes. 14. A method for the treatment of latent autoimmune diabetes in the adults by administering an effective amount of an antagonist of IL-21; 15. A method for prolonging the remission phase in patients with newly diagnosed type 1 diabetes by administering an effective amount of an antagonist of IL-21; 16. A method for reducing the secondary failure rate of treatment with orally active hypoglycaemic agents and / or postponing the need for insulin therapy in islet cell antibody (ICA), insulin antibody, heat shock protein (hsp) 60 antibody and / or GAD antibody positive patients with type 2 diabetes by administering an effective amount of an antagonist of IL-21.