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

Case report: Better late than never, but sooner is better: switch from CSII to sulfonylureas in two patients with neonatal diabetes due to KCNJ11 variants

Neonatal diabetes mellitus (NDM) is a rare genetic disease characterized by severe hyperglycemia requiring insulin therapy with onset mostly within the first 6 months and rarely between 6-12 months of age. The disease can be classified into transient (TNDM) or permanent neonatal diabetes mellitus (PNDM), or it can be a component of a syndrome. The most frequent genetic causes are abnormalities of the 6q24 chromosomal region and mutations of the ABCC8 or KCNJ11 genes coding for the pancreatic beta cell's potassium channel (KATP). After the acute phase, patients with ABCC8 or KCNJ11 mutations treated with insulin therapy can switch to hypoglycemic sulfonylureas (SU). These drugs close the KATP channel binding the SUR1 subunit of the potassium channel and restoring insulin secretion after a meal. The timing of this switch can be different and could affect long-term complications. We describe the different management and clinical outcome over the time of two male patients with NDM due to KCNJ11 pathogenetic variants. In both cases, continuous subcutaneous insulin infusion pumps (CSII) were used to switch therapy from insulin to SU, but at different times after the onset. The two patients kept adequate metabolic control after the introduction of glibenclamide; during the treatment, insulin secretion was evaluated with c-peptide, fructosamine, and glycated hemoglobin (HbA1c), which were within the normal range. In neonates or infants with diabetes mellitus, genetic testing is an indispensable diagnostic tool and KCNJ11 variants should be considered. A trial of oral glibenclamide must be considered, switching from insulin, the first line of NDM treatment. This therapy can improve neurological and neuropsychological outcomes, in particular in the case of earlier treatment initiation. A new modified protocol with glibenclamide administered several times daily according to continuous glucose monitoring profile indications, was used. Patients treated with glibenclamide maintain good metabolic control and prevent hypoglycemia, neurological damage, and apoptosis of beta cells during long-term administration.

Comparison of diabetes phenotype in children and their mothers with permanent neonatal diabetes mellitus carrying the same KCNJ11 variants

Objective. Mutations of the KCNJ11 gene are the most common cause of the permanent neonatal diabetes mellitus (PNDM). Majority of people with KNCJ11-PNDM have a de-novo mutation. We aimed to compare diabetes phenotype in two children and their mothers with PNDM carrying the same sulfonylurea-sensitive KCNJ11 variants.Methods. We have compared glibenclamide (sulfonylurea) dose, C-peptide, and HbA1c serum levels in two children and their mothers with PNDM up to 5.5-year follow-up. All of them were carrying a heterozygous activating KCNJ11 pathogenic variant (p.R201H in Family 1 or p.H46Y in Family 2). The mothers were initially treated with insulin and successfully switched to sulfonylurea at the age of 24 and 11 years, respectively. Both children were treated with sulfonylurea since the diagnosis of PNDM.Results. Glibenclamide dose was similar in both children (0.02-0.03 mg/kg/day), but lower compared to their mothers (0.1-0.4 mg/kg/day) (p<0.002). Fasting serum C-peptide levels were also lower in children (70-210 pmol/l) than in their mothers (263-720 pmol/l) (p<0.002), but no significant differences were observed in postprandial C-peptide levels. HbA1c was lower only in the son of SVK4 (Family 2) compared to his mother, as she had poor adherence to the sulfonylurea therapy during the first years after the sulfonylurea switch.Conclusions. Evaluation of the treatment in people with sulfonylurea-sensitive KNCJ11-PNDM should respect the age of patients together with the type of mutation and duration of diabetes at therapy start and may differ within one family.

Precision Medicine: Long-Term Treatment with Sulfonylureas in Patients with Neonatal Diabetes Due to KCNJ11 Mutations

PURPOSE OF REVIEW

The goal of this review is to provide updates on the safety and efficacy of long-term sulfonylurea use in patients with KCNJ11-related diabetes. Publications from 2004 to the present were reviewed with an emphasis on literature since 2014.

RECENT FINDINGS

Sulfonylureas, often taken at high doses, have now been utilized effectively in KCNJ11 patients for over 10 years. Mild-moderate hypoglycemia can occur, but in two studies with a combined 975 patient-years on sulfonylureas, no severe hypoglycemic events were reported. Improvements in neurodevelopment and motor function after transition to sulfonylureas continue to be described. Sulfonylureas continue to be an effective, sustainable, and safe treatment for KCNJ11-related diabetes. Ongoing follow-up of patients in research registries will allow for deeper understanding of the facilitators and barriers to long-term sustainability. Further understanding of the effect of sulfonylurea on long-term neurodevelopmental outcomes, and the potential for adjunctive therapies, is needed.

Permanent neonatal diabetes: combining sulfonylureas with insulin may be an effective treatment

BACKGROUND

Permanent neonatal diabetes caused by mutations in the KCNJ11 gene may be managed with high-dose sulfonylureas. Complete transfer to sulfonylureas is not successful in all cases and can result in insulin monotherapy. In such cases, the outcomes of combining sulfonylureas with insulin have not been fully explored. We present the case of a woman with diabetes due to a KCNJ11 mutation, in whom combination therapy led to clinically meaningful improvements.

CASE

A 22-year-old woman was found to have a KCNJ11 mutation (G334V) following diagnosis with diabetes at 3 weeks. She was treated with insulin-pump therapy, had hypoglycaemia unawareness and suboptimal glycaemic control. We assessed the in vitro response of the mutant channel to tolbutamide in Xenopus oocytes and undertook sulfonylurea dose-titration with C-peptide assessment and continuous glucose monitoring. In vitro studies predicted the G334V mutation would be sensitive to sulfonylurea therapy [91 ± 2% block (n = 6) with 0.5 mM tolbutamide]. C-peptide increased following a glibenclamide test dose (from 5 to 410 pmol/l). Glibenclamide dose-titration was undertaken: a lower glibenclamide dose did not reduce blood glucose levels, but at 1.2 mg/kg/day insulin delivery was reduced to 0.1 units/h. However, when insulin was stopped, hyperglycaemia ensued. Glibenclamide was further increased (2 mg/kg/day), but once-daily long-acting insulin was still required to maintain glycaemia. This resulted in improved HbA1c of 52 mmol/mol (6.9%), restoration of hypoglycaemia awareness and reduced glycaemic variability.

CONCLUSION

In people with KCNJ11 mutations causing permanent neonatal diabetes, and where complete transfer is not possible, consideration should be given to dual insulin and sulfonylurea therapy. This article is protected by copyright. All rights reserved.