Sulfonylurea vs insulin therapy in individuals with sulfonylurea-sensitive permanent neonatal diabetes mellitus, attributable to a KCNJ11 mutation, and poor glycaemic control.

Background: Therapy with sulfonylurea is preferable to insulin in the majority of individuals with KCNJ11 mutations, but not all of these people achieve target levels of HbA in long-term follow-up. We aimed to compare sulfonylurea therapy with insulin treatment in two sulfonylurea-sensitive individuals with a KCNJ11 mutation who had poorly controlled permanent neonatal diabetes mellitus.

Case Report: We report on two individuals with a KCNJ11 mutation (p.R201H) who are currently aged 35 (SVK1) and 21 years (SVK2). These individuals were switched from insulin to sulfonylurea in 2005. Data from the first 4 (SVK2) and 8 years (SVK1) of the follow-up showed improved diabetes control and increased quality of life for both individuals. During the following years, however, both individuals failed to retain good diabetes control (HbA ≤ 53 mmol/mol; 7.0%). We therefore changed the therapy to a combination of insulin and sulfonylurea in both individuals, or to insulin monotherapy in SVK1, and compared the effects on HbA with those of sulfonylurea monotherapy. HbA levels in both individuals worsened after adding insulin to sulfonylurea [67 mmol/mol (8.3%) vs 77 mmol/mol (9.2%) in SVK1 and 106 mmol/mol (11.8%) vs 110±19 mmol/mol (12.2±1.7%) in SVK2], and after switching to only insulin therapy in SVK1 [57 mmol/mol (7.4%) vs 62 mmol/mol (7.8%)] when compared with sulfonylurea monotherapy.

Discussion: Our data show that sulfonylurea monotherapy might be preferable to insulin in people with permanent neonatal diabetes mellitus sensitive to sulfonylurea even when HbA is above target.