Abstract
Decreased insulin sensitivity in patients with hypopituitarism without GH replacement (pHP-WGHR) remains conflicting in literature. It is known that these patients present a decrease in free fat mass and an increase in fat mass. Typically, these kinds of alterations in body composition are associated with a decrease in insulin sensitivity; however, there is no consensus if this association is found in pHP-WGHR. Thus, we investigated pHP-WGHR regarding insulin sensitivity by euglycemic hyperinsulinemic clamp, the gold standard method, and body composition. In a cross-sectional study, we evaluated 15 pHP-WGHR followed up in a Service of Neuroendocrinology and 15 individuals with normal pituitary function as a control group with similar age, gender and body mass index. Insulin sensitivity was evaluated by euglycemic hyperinsulinemic clamp and homeostatic model assessment insulin resistance (HOMA-IR). Kappa coefficient evaluated the agreement between these two methods. Percentage of fat mass, percentage of free fat mass, fat mass weight and free fat mass weight were assessed by electrical bioimpedance. The pHP-WGHR presented similar insulin sensitivity to control group by euglycemic hyperinsulinemic clamp, both by the M-value, (p = 0.0913) and by the area under the glucose infusion rate curve, (p = 0.0628). These patients showed lower levels of fasting glycemia (p = 0.0128), insulin (p = 0.0007), HOMA-IR (p = 0.009). HOMA-IR shows poor concordance with euglycemic hyperinsulinemic clamp (Kappa = 0.16) in pHP-WGHR, while in the control group the agreement was good (Kappa = 0.53). The pHP-WGHR presented higher values of percentage of fat mass (p = 0.0381) and lower values of percentage of free fat mass (p = 0.0464) and free fat mass weight (0.0421) than the control group. This study demonstrated that the insulin sensitivity evaluated by euglycemic hyperinsulinemic clamp in pHP-WGHR was similar to individuals with normal pituitary function, despite the pHP-WGHR presenting higher fat mass percentage. HOMA-IR was not a good method for assessing insulin sensitivity in pHP-WGHR.
Highlights
Hypopituitarism (HP) results from complete or partial deficiency in pituitary hormones from several etiologies and includes adrenal insufficiency, hypothyroidism, hypogonadism, growth hormone deficiency (GHD) and rarely diabetes insipidus [1]
Due to these contradictory results and scarce studies with the gold standard method to evaluate insulin sensitivity, euglycemic hyperinsulinemic clamp, we performed a study using this method in patients with hypopituitarism without growth hormone replacement compared to a control group composed by individuals with normal pituitary function paired by body mass index (BMI), gender, and age and we evaluated the characteristics of body composition in these groups
HP, Hypopituitarism; BMI, body mass index; F-insulin, Fasting insulin; F-Glycemia, Fasting Glycemia; homeostatic model assessment insulin resistance (HOMA-IR), homeostatic model assessment of insulin resistance; M/free fat mass (FFM), Mvalue normalized per kg Free Fat Mass; M/FFM/Gly, M-value normalized per kg Free Fat Mass and Glycemia; percentage of fat mass (PFM), Percentage of Fat Mass; percentage of free fat mass (PFFM), Percentage of Free Fat Mass; basal metabolic rate (BMR), Basal Metabolic Rate
Summary
Hypopituitarism (HP) results from complete or partial deficiency in pituitary hormones from several etiologies and includes adrenal insufficiency, hypothyroidism, hypogonadism, growth hormone deficiency (GHD) and rarely diabetes insipidus [1]. We highlight that the authors of the mentioned studies that evaluated insulin sensitivity used different methods of evaluation to the homeostatic model assessment (HOMA-IR), the frequently sampled intravenous glucose tolerance tests with minimal model analysis or euglycemic hyperinsulinemic clamp (EHC) [4,5,6,7,8,9,10,11,12] Due to these contradictory results and scarce studies with the gold standard method to evaluate insulin sensitivity, euglycemic hyperinsulinemic clamp, we performed a study using this method in patients with hypopituitarism without growth hormone replacement compared to a control group composed by individuals with normal pituitary function paired by BMI, gender, and age and we evaluated the characteristics of body composition in these groups
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