Endocrine Abstracts

Cystic fibrosis related diabetes (CFRD) is the commonest co-morbidity in CF leading to increased mortality rates. The pathophysiology includes pancreatic fibrosis, reduction in α and ß-cell mass, delayed insulin secretion and variable insulin insensitivity. Insulin production can fluctuate with progression over time to an insulinopenic state. We report two cases of young people with CFRD with high insulin requirements, poor glycaemic control and improvement with the introduction of insulin pump therapy.

Cases: Two 15-year-old females were diagnosed with CFRD following positive OGTT and elevated HbA1c (7.1 and 6.5% respectively). They were started on insulin (0.13 units/kg per day and 0.03 units/kg per day). Each subsequently presented on a weekend to their local A&E unwell with blood glucose >20 mmol/l, polyuria, polydipsia and negative ketones. They were advised that CFRD did not need acute treatment and discharged. On admission to their tertiary centre they required >2 units/kg per day of IV insulin sliding scale, suggesting probable hepatic insulin insensitivity and acute decompensation at a time of illness.

Case 1 opted for insulin pump therapy and case 2 opted for Multiple Daily Injections. Case 2, after initial improvement found adherence to be an issue, particularly given her eating patterns and multiple injection requirement. A decision was taken to support her request to start insulin pump therapy.

Improvement in HbA1c from pump start to 6 months was 8.0 to 7.7% (Case1) and 14.0–8.6% (Case 2). Δ BMI SDS 0.28–0.11 (Case1) and −2.44 to −0.93 (Case 2). Insulin requirements on the pump at 6 months were 0.5 units/kg per day (Case1) and 0.6 units/kg per day (Case 2). This was a 75% reduction in insulin requirements from acute presentation.

Each reported a subjective improved quality of life and reduced burden of diabetes with respect to CF care compared to injection therapy.

Discussion: Acute, symptomatic hyperglycaemia in CFRD should be acted on promptly. Hepatic insulin insensitivity in illness can lead to high insulin requirements which reduce with treatment. An insulin pump is a valuable tool in CFRD.