Acromegaly Associated with Type 2 Diabetes Showing Normal IGF-1 Levels under Poorly Controlled Glycemia

Abstract

Abstract. Acromegaly is caused by excessive secretion of growth hormone (GH), and a resultant persistent elevation of insulin-like growth factor-1 (IGF-1) levels. Diabetes mellitus is accompanied in some acromegalic patients with insulin resistance. We encountered a type-2 diabetic patient who had a poorly controlled glycemic state and was diagnosed as acromegaly with normal IGF-1 levels. The patient showed definite acromegalic features. However, in the first screening test, GH levels were high and IGF-1 levels were inappropriately normal so the results were not close to the diagnosis of acromegaly. After moderate glycemic control, an oral glucose suppression test was performed, showing no suppressed GH response. TRH test revealed paradoxical increases in growth hormone levels and a brain MRI discovered a pituitary adenoma. After several-months insulin treatment, IGF-1 levels were increased to the abnormal state and GH levels were decreased without treatment for acromegaly. Here we report the rare case of acromegaly that presents inappropriately normal IGF-1 levels at the time of diagnosis in uncontrolled type 2 diabetic patient and shows increased IGF-1 levels after glycemic control with insulin therapy. When evaluating acromegaly in type 2 diabetes under poorly controlled glycemia, cautious IGF-1 analysis is needed after sufficient glycemic control.

Acromegaly with Normal IGF-1 Levels Probably due to Poorly Controlled Diabetes Mellitus

“…In emaciated patients such as anorexia nervosa, lower circulating levels of GH binding-proteins (GHBP) were reported to mediate GH resistance (Herington et al 1986;Counts et al 1992;Argente et al 1997). There has been one report on a patient with acromegaly and diabetes mellitus with poorly controlled glycemia (Lim et al 2007). In this case (Lim et al 2007), serum GH levels were elevated but serum IGF-1 levels were normal.…”

“…There has been one report on a patient with acromegaly and diabetes mellitus with poorly controlled glycemia (Lim et al 2007). In this case (Lim et al 2007), serum GH levels were elevated but serum IGF-1 levels were normal. However, glycemic control with insulin Fig.…”

“…Furthermore, collecting the blood sample for the IGF-1 measurement is easier, because it does not require resting, and serum IGF-1 level shows no diurnal variation. Serum IGF-1 levels, however, have variations for age and gender, and are suppressed in some diseases and conditions including diabetes mellitus with poorly controlled glycemia (Ross et al 1991;Bentham et al 1993;Lim et al 2007).…”

Biochemical Evaluation of Patients with Active Acromegaly and Type 2 Diabetes Mellitus: Efficacy and Safety of the Galanin Test

“…Poorly controlled diabetes in non-acromegalic patients is associated with dysregulation of the GH/IGF-1 axis, leading to an increase in serum GH concentrations [6,7,8]. Serum IGF-1 levels, a useful marker of GH excess, may also be difficult to interpret in the presence of diabetes mellitus [8, 9]. In fact, although serum IGF-1 values are mostly in the normal range, increased concentrations have sometimes been found in patients with diabetes, and microvascular complications or inappropriately normal IGF-1 levels may be found in patients with acromegaly and uncontrolled type 2 diabetes [9,10,11].…”

“…Serum IGF-1 levels, a useful marker of GH excess, may also be difficult to interpret in the presence of diabetes mellitus [8, 9]. In fact, although serum IGF-1 values are mostly in the normal range, increased concentrations have sometimes been found in patients with diabetes, and microvascular complications or inappropriately normal IGF-1 levels may be found in patients with acromegaly and uncontrolled type 2 diabetes [9,10,11]. Moreover, diabetes mellitus hinders the use of OGTT as a diagnostic tool in acromegaly either because this test is not well tolerated in patients with baseline hyperglycemia or because of the occurrence of false-positive results [2].…”