Group A  Inclusion Criteria:  Age between 65 and 80 years. Patients with recently diagnosed T2DM (last 6 months), according to the WHO classification. Patients in whom written informed consent has been obtained for participation in the study.  Exclusion Criteria:  HbA1c ≥ 9% Metformin treatment in the past 6 months Creatinine greater than 1.2 and glomerular filtration rate less than 40 Serious systemic disease not related to obesity, including any type of cancer, severe kidney disease or liver disease, and known type 1 diabetes. Systemic diseases with intrinsic inflammatory activity such as rheumatoid arthritis, Crohn's disease, asthma, or chronic infection (e.g., HIV, active tuberculosis) or any type of infectious disease. Current treatment for malignant neoplasia, other than basal cell or squamous cell skin cancer. Class III or IV heart disease, known ischemic cardiovascular disease Kidney failure, history of kidney transplant, or current dialysis treatment Serum liver enzymes (GOT, GPT) above twice the upper limit of normal. Obvious signs or symptoms of liver disease, acute or chronic hepatitis. Chronic constipation (stool habit ≥ 7 days) Pregnancy or breastfeeding Treatments that affect glucose metabolism or the intestinal microbiota with biguanides, sulfonylurea secretagogues or non-sulfonylurea secretagogues, insulin sensitizers, insulin, thiazolidinediones, alpha glucosidase inhibitors, incretin mimetics, Dipeptidyl peptidase IV inhibitors, use of cathartics. Chronic anti-inflammatory treatment with steroidal drugs (during the previous 3 months). Symptoms and / or clinical signs of infection in the previous month. Antibiotic, antifungal or antiviral treatment active in the previous 3 months. Treatment with glucocorticoids chronic or during the 2 months prior to inclusion in the study. Treatment with a weight loss product during the previous two months Immunosuppressant treatment. Excessive alcohol consumption (alcohol intake greater than 40 g per day (women) or 80 g / day (men)) either acute or chronic, or drug use. History of drug or alcohol abuse. Patients with severe eating disorders History of alterations in iron balance (known chronic hemoglobinopathies or anemia, genetic hemochromatosis, hemosiderosis from any cause, atransferrinemia, paroxysmal nocturnal hemoglobinuria). Important psychiatric history. Participation in any other study. People whose freedom is under legal or administrative requirement.  Group B  Inclusion Criteria:  Age between 65 and 80 years. Patients with long-term T2DM according to the WHO classification Patients in whom written informed consent has been obtained for participation in the study.  Exclusion Criteria:  HbA1c ≥ 9% Creatinine greater than 1.2 and glomerular filtration rate less than 40 Serious systemic disease not related to obesity, including any type of cancer, severe kidney disease or liver disease, and known type 1 diabetes. Systemic diseases with intrinsic inflammatory activity such as rheumatoid arthritis, Crohn's disease, asthma, or chronic infection (e.g., HIV, active tuberculosis) or any type of infectious disease. Current treatment for malignant neoplasia, other than basal cell or squamous cell skin cancer. Class III or IV heart disease, known ischemic cardiovascular disease. Kidney failure, history of kidney transplant, or current dialysis treatment Serum liver enzymes (GOT, GPT) above twice the upper limit of normal. Obvious signs or symptoms of liver disease, acute or chronic hepatitis. Chronic constipation (stool habit ≥ 7 days) Pregnancy or breastfeeding Chronic anti-inflammatory treatment with steroidal drugs (during the previous 3 months). Symptoms and / or clinical signs of infection in the previous month. Antibiotic, antifungal or antiviral treatment active in the previous 3 months. Treatment with glucocorticoids chronic or during the 2 months prior to inclusion in the study. Treatment with a weight loss product during the previous two months. Immunosuppressant treatment. Excessive alcohol consumption (alcohol intake greater than 40 g per day (women) or 80 g / day (men)) either acute or chronic, or drug use. History of drug or alcohol abuse. Patients with severe eating disorders History of alterations in iron balance (known chronic hemoglobinopathies or anemia, genetic hemochromatosis, hemosiderosis from any cause, atransferrinemia, paroxysmal nocturnal hemoglobinuria). Important psychiatric history. Participation in any other study. People whose freedom is under legal or administrative requirement.