The glycation extent of human hemoglobin is under control of the Maillard reaction, a chemical interaction between an amino acide and a reducing sugar. About 5% ( 31.1 mmol/mol) of hemoglobin molecules secluded in a red blood cell are glycated; excessive values > 6.5% point to prediabetes or overt diabetes mellitus. To ascertain the diagnosis doctors prescribe oral glucose tolerance upon which glucose concentrations in blood increase - how much HbA1c reacts under these circumstances is ill known.

Medical laboratory assays for delineation of impaired glucose metabolism and overt diabetes mellitus, beyond measurement of (fasting) blood serum or plasma glucose levels, include extent of hemoglobin A1c glycation, concentration of fructosamines, insulin concentrations to calculate the homeostasis model assessment (HOMA) index and other clinically putative biomarkers of glucose homoeostasis. HbA1c levels form now part of routine elucidation of metabolic disorders and are used for therapy monitoring. Initially used to monitor glucose levels in follow-up care of diabetics it is considered as a track marker of ups and downs of blood glucose concentrations. Its behavior under the 2 h period of oral glucose tolerance tests (OGTT) is ill known - most clinicians believe the glycation extent will not change. Since the dynamics of glycation is temperature dependent,non-febrile patients under OGTT likely keep their glycation extent between time zero and 120 min after glucose charge constant but this has not been investigated and with the sensitive lab assays for HbA1c now in use we postulate a significant increase in glycation. The Patient Registry includes recruited children and adults sick from diabetes, overweight or metabolic syndrome as a whole. Three medical offices will address their patients to the VidyMed lab to perform the OGTT framed by lab assays on venous blood samples

Inclusion Criteria:

• apparently healthy subjects or subjects supposedly experiencing a metabolic disease (e.g. prediabetes) Subjects with asked for fasting blood glucose

Exclusion Criteria:

• current steroid use thyroid dysfunction (free-thyroxin levels < 9 or > 19 pmol/L, hsCRP > 10 mg/L hospitalized

(i) Those suspected to suffer from the metabolic syndrome including high blood pressure, high blood sugar, excess of body fat and increased cholesterol levels (ii) patients with overt impaired carbohydrate metabolisms, under treatment and tested for follow up

peer reviewed publication in an anglophone scientific journal. No IPD sharing