Provided herein are methods of treating a patient with severe insulin resistance. The methods comprise administering to a patient in need thereof a therapeutic amount of a GCG/GCGR signaling pathway inhibitor, such that blood glucose or beta-hydroxybutyrate levels are lowered or that the severe insulin resistance is mediated, or a condition or disease characterized by severe insulin resistance is mediated, or at least one symptom or complication associated with the condition or disease is alleviated or reduced in severity. The GCG/GCGR signaling pathway inhibitor can be a small molecule inhibitor of the signaling pathway, an antisense inhibitor of the signaling pathway, a GCG neutralizing monoclonal antibody, a GCGR antagonist, a peptide inhibitor of the signaling pathway, a DARPin, a Spiegelmer, an aptamer, engineered Fn type-III domains, etc. The therapeutic methods are useful for treating a human suffering from severe insulin resistance.