Authors and collaborators have continued clinical practice and research on diabetes for long, and begun Low Carbohydrate Diet (LCD) at first in Japan. We have proposed super-, standard-, petite-LCD methods with 12%, 26%, 40% of carbohydrate, and developed medical and social LCD movement by Japanese LCD promotion association (JLCDPA). For research protocol, subjects were 10 healthy young medical staff. Two tests were 75gOGTT and meal tolerance test (MTT) of breakfast of super-LCD with 300kcal and 6g of carbohydrate. Blood glucose and immunoreactive insulin (IRI) were measured at 0 min and 30 min. Results of glucose and IRI in median value (0-30min) showed as follows: i) OGTT; 89.5 mg/dL to 130.5 mg/dL, 5.1 μU/mL to 40.6 μU/mL, ii) MTT; 93.5 mg/dL to 84.5 mg/dL, 4.9μU/mL to 10.6 μU/mL (significant increase, p<0.05). The increments of IRI for GTT (carbo-75g) and MTT (carbo-6g) were analyzed. There was a significant correlation between increments of IRI in GTT and MTT (p<0.05). Blood glucose in MTT tended to decrease from 0 min to 30 min. These results suggested that insulin secretion would be sufficient and relatively excessive for 6g of carbohydrate amount
