Various etiologies of genetic hypoglycemias are classified according to the time of manifestation [Table 5].[29] The laboratory investigations during symptomatic hypoglycemia should include blood counts, C-reactive protein (CRP), liver function tests, creatine kinase (CK), uric acid, triglycerides, blood gases and electrolytes, lactate, and ammonia, ketones in urine, organic acids (in first urine sample after hypoglycemia), plasma amino acids, carnitine and acylcarnitines, plasma insulin, C-peptide, glucagons, cortisol, IGF-1 and isoelectric focussing for transferrin (if indicated). The gene discussed is INS; the disease is Hypoglycemia.