Hypoglycemic Agents/administration & dosage; Urea/administration & dosage; Acute Disease; Administration, Oral; Adult; Aged; Alkaline Phosphatase/urine; Aspartate Aminotransferases/blood; Bilirubin/urine; Blood Cell Count; Blood Glucose/analysis; Blood Urea Nitrogen; Cholesterol/blood; Chronic Disease; Clinical Trials as Topic; Cyclohexanes/administration & dosage; Cyclohexanes/toxicity; Diabetes Mellitus/blood; Diabetes Mellitus/drug therapy; Female; Glucose Tolerance Test; Humans; Hypoglycemic Agents/pharmacology; Hypoglycemic Agents/toxicity; Insulin/blood; Insulin/metabolism; Insulin Secretion; Male; Middle Aged; Pancreas/drug effects; Phenformin/therapeutic use; Placebos; Sulfones/administration & dosage; Sulfones/toxicity; Thymol/analysis; Urea/toxicity