INS and type 1 diabetes mellitus: This case report demonstrates that long-term (10-year) therapy with a ketogenic diet in a person with type 1 diabetes has considerable therapeutic benefits by causing a marked improvement in glycemic control (mean HbA1c decreased from 6.8% [50.8 mmol/mol] to 5.5% [36.6 mmol/mol]) and a 43% decrease in insulin requirements without adverse effects (Fig. 1).