Reevaluating the Need for Routine IGF-1 Screening in Poorly Controlled Type 2 Diabetes Mellitus

Acromegaly is commonly associated with diabetes mellitus (DM), and its prevalence may be higher among individuals with type 2 DM than in the general population. This study aimed to assess the frequency of acromegaly in patients with poorly controlled type 2 DM.

This cross-sectional study included 504 patients (mean age: 57.7 ± 10.8 years) with uncontrolled type 2 DM (HbA1c > 8%) despite at least 1 year of insulin treatment (insulin alone or oral anti-diabetic drugs together with insulin). Serum insulin-like growth factor 1 (IGF-1) levels were measured for screening. In patients with elevated IGF-1, growth hormone (GH) levels were assessed by oral glucose tolerance test (OGTT). Pituitary magnetic resonance imaging (MRI) was performed in cases with persistently elevated IGF-1 and inadequate GH suppression or discordant post-glucose GH levels.

The median duration of DM was 9 (3-15) years, and the mean HbA1c was 11.12% ± 2.30%. Elevated serum IGF-1 levels were found in 2 of the 504 patients (0.39%). Both underwent OGTT for GH evaluation. One patient showed appropriate GH suppression, and the other demonstrated borderline GH suppression (a nadir GH of 0.88 ng/mL) with a 4 × 3 mm cystic pituitary lesion on MRI. However, given the absence of acromegalic clinical features and lack of biochemical confirmation, acromegaly was not diagnosed in either case.

Routine IGF-1 screening in all patients with poorly controlled type 2 DM has limited diagnostic yield. IGF-1 testing should be reserved for patients exhibiting clinical features or phenotypic suspicion of acromegaly.