Acute illness in patients with concomitant Addison's disease and type 1 diabetes mellitus: Increased incidence of hypoglycaemia and adrenal crises.

BACKGROUND: Patients with Addison's disease (AD) and comorbid type 1 diabetes mellitus (T1DM) are at increased risk of certain acute metabolic disorders relative to patients with one of these conditions only. The reasons for this are unknown. METHODS: All attendances for acute illness by AD patients at the emergency department of a Sydney hospital between 2000 and 2017 were reviewed. Physiological parameters and illness management strategies were compared between AD patients, those with T1DM and AD combined, and a control group of patients with T1DM. RESULTS: There were 39 presentations for an acute medical illness by 20 non-diabetic AD (28 attendances) and 5 diabetic AD patients (11 presentations) and 40 attendances by 10 T1DM controls. In AD patients, 17 (43.6%) attendances were medically-diagnosed adrenal crises (AC) (63.6% [n=7] in diabetic AD and 35.7% [n=10] in non-diabetic AD). This corresponded to an estimated incidence of 12.5 AC/100 patient years (PY) for diabetic AD patients compared to 4.7 AC/100PY for non-diabetic AD patients (p<0.05). Glucocorticoid stress doses preceded 61.5% (n=24) of all attendances. Patients who used stress doses had more presentations than those who did not (2.0±1.3 vs 1.2±0.5, p=0.01). Diabetic AD patients had a lower mean blood glucose level on presentation (5.6+/-3.9mmol/l) than the T1DM control sample (11.6+/-6.2mmol/l) p<0.001. No T1DM patients had hypoglycaemia in the 3.0-3.9 mmol/l range but 2 (18.2%) of the diabetic AD patients had presenting blood glucose levels in this category, (p<0.05). Hyperglycaemia was more common among T1DM control patients (62.5%, n=26) than diabetic AD patients (18.2%, n=2), p<0.01. CONCLUSION: AD patients with T1DM have a higher incidence of adrenal crisis (AC) and hypoglycaemia than non-diabetic AD patients, and a lower incidence of hyperglycaemia than those with T1DM alone. This information may be of value in counselling patients with T1DM and AD about AC and hypoglycaemia prevention.