Distinct Pituitary-Adrenal Responses to Hypoglycemia in Type 1 and Type 2 Diabetes

Hypoglycemia remains a major barrier to optimal glycemic control in diabetes. Counter-regulatory hormonal responses, particularly those involving the pituitary and adrenal systems, play a central role in mitigating hypoglycemia, yet differences between diabetes subtypes are not well characterized. We aimed to investigate pituitary-target gland responses to hypoglycemia in patients with type 2 diabetes mellitus (T2DM) and type 1 diabetes mellitus (T1DM).

We enrolled drug-naive patients with newly diagnosed T2DM or T1DM, along with controls who did not have diabetes. Participants with diabetes received insulin pump therapy until normoglycemia was achieved. Hyperinsulinemic euglycemic-hypoglycemic clamps were then performed in all participants. Hormonal profiles of the pituitary-adrenal axis and C-peptide were serially measured during the clamps.

During hypoglycemic clamps, C-peptide, thyroid-stimulating hormone, estradiol, and testosterone decreased, whereas prolactin, adrenocorticotropic hormone (ACTH), cortisol, and growth hormone (GH) increased significantly according to repeatedmeasures analysis of variance (ANOVA) (P<0.05 for all). Compared to controls and T2DM, patients with T1DM exhibited elevated basal GH (P=0.002) and an exaggerated GH response to hypoglycemia (P=0.002), with earlier onset and sustained elevation. In contrast, patients with T2DM showed higher ACTH (P=0.024) and cortisol (P=0.043) levels during hypoglycemia compared to controls and T1DM. Relative to the T1DM group, the T2DM group demonstrated lower testosterone and higher estradiol levels during hypoglycemia (P<0.001 for both).

Distinct diabetes subtypes demonstrate divergent pituitary-adrenal counter-regulatory responses to hypoglycemia, suggesting unique pathogenic mechanisms contributing to glycemic variability. The exaggerated GH response in T1DM may aggravate glucose fluctuations, whereas elevated ACTH and cortisol in T2DM could perpetuate insulin resistance.