Endocrine Abstracts

Introduction: Acromegaly is the result of chronic growth hormone (GH) excess, which leads to decreased insulin sensitivity and increased glucose production, to the extent that the impaired blood glucose regulation (IGR) can be recognised as Type 2 Diabetes Mellitus (T2DM). This project looked to identify whether patients were adequately screened or identified as having T2DM on diagnosis of acromegaly. The secondary aim was to determine whether acromegaly treatment affected glycaemic control in our cohort of patients.

Methods: We included ninety-five patients treated for acromegaly in University Hospital Wales, UK, between 1999 and 2020. Screening IGF-1 and nadir growth hormone following a 75g oral glucose tolerance test (OGTT) results were taken as evidence of diagnosis of acromegaly. HbA1c at the time of acromegaly diagnosis (Pre), post acromegaly treatment (Post) and most recent recording (Latest) were taken as a representation of glycaemic control. Analysis of this data and the graphs produced was done using Rstudio version 4.1.0, a statistical software.

Results: Nineteen patients were diagnosed and treated for diabetes mellitus before the diagnosis of acromegaly was made. Six patients were newly identified to have a blood glucose within diabetic range at OGTT (2 h plasma glucose >=11.1 mmol/l) and 5 of them underwent subsequent HbA1c testing. However, this was not the case for those with an impaired glucose regulation (IGR) (two-h glucose=7.8 -11.1 mmol/l and/or fasting glucose=6.1-6.9 mmol/l) with only 2 out of 16 having a HbA1c result recorded. From the sub-cohort of 26 patients who were identified as having a raised blood glucose measurement on OGTT and a HbA1c reading at acromegaly diagnosis, 15 (58%) had HbA1c reading done 3-6 months after surgical treatment. The results showed a decrease in mean HbA1c post treatment (mean Pre HbA1c=63.5 mmol/mol, mean Post HbA1c =45.7 mmol/mol, P<0.005). 22 out of 26 patients (85%) who had “Pre”, “Post” and “Latest” HbA1c readings were analysed to determine if acromegaly treatment has a long-term effect on glycaemic control. This showed significant decrease between Pre HbA1c and Post HbA1c (P=0.0210). There was no significant difference between Post HbA1c and Latest HbA1c (P=1.00).

Conclsion: IGR is a risk factor for diabetes mellitus and cardiovascular disease. Our data showed that improvements could be made in the care of patients with IGR detected in the diagnostic OGTT for acromegaly and in the follow up HbA1c monitoring for those with established diabetes mellitus or IGR who underwent acromegaly treatment.