What are the secondary causes of growth hormone (GH) excess in diabetes mellitus (DM)?

From the Guidelines

To evaluate for secondary causes of growth hormone excess in diabetes, a comprehensive approach including clinical assessment, laboratory tests, imaging studies, and genetic testing is essential, with a strong recommendation for genetic assessment in all children and young people with a pituitary adenoma, as stated in the 2024 consensus guideline 1. When evaluating for secondary causes of growth hormone excess in diabetes, several key steps should be taken:

• Start with a thorough clinical assessment including medical history and physical examination focusing on acromegalic features.
• Order laboratory tests including insulin-like growth factor-1 (IGF-1) levels, which serve as a reliable screening tool, and a growth hormone (GH) suppression test using oral glucose tolerance test (OGTT) where failure to suppress GH below 1 ng/mL suggests excess, as supported by the understanding of endocrinopathies and their impact on diabetes 1.
• Imaging studies are essential, primarily MRI of the pituitary to identify adenomas, which are the most common cause of GH excess.
• Additional imaging may include chest and abdominal CT scans to detect ectopic GH-producing tumors.
• Evaluate for conditions that can mimic or exacerbate GH excess, such as liver or kidney disease, malnutrition, and certain medications.
• Consider genetic testing for rare hereditary conditions like Multiple Endocrine Neoplasia type 1 (MEN1) or Carney complex, given the high prevalence of genetic abnormalities in somatotroph and lactotroph tumors, as highlighted in the 2024 guideline 1. This approach is crucial for identifying the underlying cause of GH excess, which is vital for appropriate management, as chronic GH elevation can worsen insulin resistance and complicate diabetes control. The 2024 consensus guideline strongly recommends genetic assessment for all children and young people with a pituitary adenoma, emphasizing the importance of genetic testing in the diagnosis and management of GH excess 1.

From the Research

Evaluating Secondary Causes of Growth Hormone Excess in Diabetes

To evaluate for secondary causes of growth hormone excess in diabetes, consider the following:

• Growth hormone-secreting pituitary adenomas, which can cause acromegaly, a condition characterized by excessive growth hormone production 2, 3, 4
• The role of growth hormone in diabetes care, including its potential involvement in the development of diabetic retinopathy and microvascular disease 5
• The relationship between growth hormone secretion and insulin-like growth factor-I (IGF-I) levels, which can contribute to the development of diabetic complications 5

Diagnostic Considerations

When evaluating patients with diabetes for secondary causes of growth hormone excess, consider:

• Measuring serum IGF-I levels to assess growth hormone activity 2, 3, 4
• Evaluating for signs and symptoms of acromegaly, such as tissue overgrowth and glucose dysregulation 2, 3, 4
• Assessing for other conditions that may contribute to growth hormone excess, such as pituitary adenomas or other endocrine disorders 6

Treatment Implications

Treatment of growth hormone excess in diabetes may involve:

• Surgical resection of pituitary adenomas 2, 3, 4
• Medical therapy with somatostatin analogs, dopamine agonists, or growth hormone receptor antagonists 2, 3, 4
• Management of glucose dysregulation and other metabolic complications associated with growth hormone excess 5, 6