High prevalence of steroid-induced glucose intolerance with normal fasting glycaemia during low-dose glucocorticoid therapy: an oral glucose tolerance test screening study.

Objectives: To evaluate the prevalence and risk factors of new-onset glucose metabolism impairment using an oral glucose tolerance test (OGTT) in patients with normal fasting glycaemia on long-term glucocorticoid (GC) treatment.

Methods: An OGTT was performed in 150 patients without a previous history of pre-diabetes or diabetes who were diagnosed with inflammatory rheumatic diseases and treated with GCs >3 months. All participants underwent clinical and biochemical evaluation for risk factors of diabetes: age, sex, current and cumulative dose of steroids, treatment duration, waist circumference, BMI, Homeostatic Model Assessment for Insulin Resistance, fasting insulin concentration, family history of diabetes, CRP, 28-joint DAS with CRP, type of connective tissue disease and trunk fat percentage measured by DXA. Logistic regression analysis was conducted to evaluate the association between the presence of impaired glucose tolerance (IGT) in the OGTT and analysed risk factors.

Results: A total of 102 patients (68%) had fully normal glucose tolerance. Diabetes, isolated impaired fasting glucose, isolated IGT and combined impaired fasting glucose + IGT was diagnosed in 3.3, 4.67, 19.33 and 4.67% of patients, respectively; 20% of participants had IGT or diabetes despite normal fasting glucose concentration. The median cumulative dose and current dose (5 mg) of GCs and treatment duration were similar compared with the normal glucose tolerance group. In a multivariate logistic regression model, only older age (particularly ≥50 years of age) and trunk fat percentage remained significant factors predicting IGT or diabetes in the OGTT.

Conclusion: New-onset GC-induced glucose intolerance, even in patients on long-term low-dose treatment, is prevalent despite normal fasting glucose concentration and patients should be screened with an OGTT despite the absence of classic risk factors of diabetes.