Objective Hyperglucagonemia is one of characteristics associated with type 2 diabetes, but little is known of its role in the development of type 2 diabetes (T2DM). We examined the glucagon response to meal ingestion in Japanese subjects with differing glucose tolerance. Methods T2DM (n = 47; HbA1c 6.7 ± 0.1%; duration 4.1 ± 0.8 years), IGT (n = 24; HbA1c 5.9 ± 0.1%) and NGT (n = 35; HbA1c 5.6 ± 0.0%) were subjected to oral glucose and meal tolerance tests (OGTT and MTT) on two separate days. Results By OGTT, significant and continuous glucagon suppression 20-120 min after glucose load in NGT and IGT (P < 0.01 vs 0min) was detected. On the other hand, T2DM showed a significant glucagon elevation 10 min after glucose load that remained significantly higher compared to that of NGT (P < 0.01 vs NGT). By MTT, glucagon elevation with a peak 10 min after meal ingestions, which decreased with time in both NGT and IGT, was detected. T2DM showed fasting and postprandial glucagon significantly higher compared to that of NGT. Areas under the curve of glucagon did not differ between NGT and IGT in OGTT and MTT. Conclusion These finding suggest that dysregulated glucagon secretion is secondary to T2DM.