Endocrine Abstracts

Objective: To report a case of a patient diagnosed with latent autoimmune diabetes of adulthood (LADA) based on clinical presentation and positive glutamic acid decarboxylase antibodies (GAD-abs) that converted to antibody negative diabetes after combined treatment with sitagliptin and vitamin D.

Methods: A 31-year-old male presented at the emergency room with symptoms of polyuria, polydipsia, and weight loss. Blood glucose was 300 mg/dl with mild ketonuria and HbA1c was 9.6%. The patient had a family history of autoimmune disorders. Declining insulin therapy he was initially treated with gliclazide and metformin. Owing to the patients poor glycemic control a GAD-abs titer measurement was performed and the results came back positive at 32 U/ml (NV <5 U/ml), so a LADA diagnosis was established. Other blood tests came back normal except from a low 25-OH-vitD level of 11 ng/ml (NV >30 ng/ml). Declining insulin therapy, he was advised to discontinue gliclazide and a combination of metformin 850 mg/sitagliptin 50 mg twice daily along with vitamin D supplementation (2000 IU/day) was prescribed.

Results: At follow-up visits, his HbA1c was 6.1% at 6 months and 5.4% at 11 months. His GAD-abs level declined by 86% within normal range at 4.2 U/ml. Two years later, receiving the same treatment, he has negative GAD-abs, his HbA1c is 5.2% and he maintains an excellent glycaemic profile.

Conclusion: Both vitamin D analogues and dipeptidyl peptidase 4 (DPP4) inhibitors have been shown to improve β-cell function and attenuate autoimmunity in type 1 diabetic mouse models. To our knowledge this is the first case that combined treatment with sitagliptin and vitD in a patient with LADA reverted the phenotype and preserved an excellent glycaemic control without the use of insulin 24 months after diagnosis.