Type 2 diabetes is tightly associated with overweight and obesity. Inflammatory processes are crucial triggers for insulin resistance that paves the way to type 2 diabetes. In a previous study the investigators have shown that n-3 polyunsaturated fatty acids diminish adipose tissue inflammation in morbidly obese non-diabetic subjects. in this observational study the investigators will apply n-3 polyunsaturated fatty acids as addition to a protein-enriched diet with low glycemic index to overweight and obese patients with insulin resistance, prediabetes and manifest type 2 diabetes over up to 6 months. Primary efficacy parameters are changes from baseline in HbA1c and body weight for for type 2 diabetes and all other patients, respectively.

Inclusion Criteria:

• overweight or obesity AND
• insulin resistant OR pre-diabetes OR type 2 diabetes

Exclusion Criteria:

• changes in anti-diabetic medication in the lat two months
• acute illness during the last two weeks
• HIV infection
• hepatitis of other clinically significant hepatic disease other than non-alcoholic hepatic steatosis
• severe or insufficiently treated cardiovascular, renal (GFR-MDRD < 60 ml/min) or pulmonary disease
• Macroproteinuria (> 300 mg/g creatinine)
• clinically significant or insufficiently treated thyroid disease
• anemia
• active malignant disease
• inborn or acquired coagulopathy

overweight to obese insulin resistant, prediabetic and diabetic patients