Background and Aims: We propose a novel method to realize an artificial pancreas with an insulin pump and a glucagon pen. We show that the benefits of a second hormone can also be reached with pen injections, which makes a second pump for glucagon unnecessary. Method: An existing simulation model for the human glucoregulatory system was used to develop a predictive control that administers insulin doses and, in case of impending hypoglycemia, calculates an optimal amount of glucagon for pen injection. We considered errors in the carbohydrate (CHO) estimations for the meal announcements and tested the controller in-silico using the simulation model and data of two patients. Results: The risk of hypoglycemia associated with a CHO meal overestimation can be removed by glucagon pen injection. The injection is necessary only if the overestimation is sufficiently large (e.g. >60% for patient 128). The amount of infused insulin and the time spent in hyperglycemia is not affected by these glucagon injections, but a higher or earlier insulin delivery is possible increasing the time in the euglycemic range. Conclusion: The proposed method shows that a bihormonal controller can also be realized with a glucagon pen that is used only for the case of impending hypoglycemia. It can be used more easily than a two pump approach and could encourage diabetics to tune their BG control more aggressively because in the seldom case of extreme CHO overestimation they can rely on the safety feature of the controller.