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 nondiabetic 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 nondiabetic 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 nondiabetic AD patients (P < .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 = .01). Diabetic AD patients had a lower mean blood glucose level on presentation (5.6 ± 3.9 mmol/L) than the T1DM control sample (11.6 ± 6.2 mmol/L) P < .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 < .05). Hyperglycaemia was more common among T1DM control patients (62.5%, n = 26) than diabetic AD patients (18.2%, n = 2), P < .01.

Conclusion: Addison's disease patients with T1DM have a higher incidence of adrenal crisis (AC) and hypoglycaemia than nondiabetic 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.