Methods for detecting glucagon antagonists through the use of recombinant DNA techniques are provided. Briefly, subsequent to the expression of glucagon analogs within suitable host cells, the analogs are exposed to a glucagon receptor coupled to a response pathway in the presence of native glucagon. A reduction in the stimulation of the response pathway resulting from the binding of the glucagon analog to the glucagon receptor relative to the stimulation of the response pathway by native glucagon alone indicates the presence of a glucagon antagonist. Glucagon antagonists identified and isolated through the methods are also provided.