Effects of Intranasal Naloxone on Hypoglycemia-Associated Autonomic Failure (HAAF) in Susceptible Individuals.

CONTEXT: Hypoglycemia-associated autonomic failure (HAAF), defined as blunting of counter-regulatory hormone and symptom responses to recurrent hypoglycemia, remains a therapeutic challenge in diabetes treatment. The opioid system may play a role in HAAF pathogenesis since activation of opioid receptors induces HAAF. Blockade of opioid receptors with intravenous naloxone ameliorates HAAF experimentally, yet is not feasible therapeutically. OBJECTIVE: To investigate the effects of opioid receptor blockade with intranasal naloxone on experimentally-induced HAAF. DESIGN: Randomized, double-blinded, placebo-controlled crossover study. SETTING: Academic research center. PARTICIPANTS: Healthy non-diabetic volunteers. INTERVENTIONS: Paired two-day studies, 5-10 weeks apart, each consisting of three consecutive hypoglycemic episodes (hyperinsulinemic hypoglycemic clamps, glucose nadir: 54 mg/dL): two on day 1 with administration of intranasal naloxone vs. placebo, followed by the third episode on day 2. MAIN OUTCOME MEASURES: Differences in counter-regulatory hormones responses and hypoglycemia symptoms between first and third hypoglycemic episodes in naloxone vs. placebo studies. RESULTS: Out of 17 participants, 9 developed HAAF, confirming variable inter-individual susceptibility. Among participants susceptible to HAAF, naloxone maintained some hormonal and symptomatic responses to hypoglycemia and prevented the associated requirement for increased glucose infusion. Unexpectedly, naloxone reduced plasma epinephrine and growth hormone responses to the first hypoglycemic episode but prevented further reduction with subsequent hypoglycemia. CONCLUSIONS: This is the first study to report that intranasal naloxone, a widely used opioid receptor antagonist, may ameliorate some features of HAAF. Further investigation is warranted into mechanisms of variable inter-individual susceptibility to HAAF and the effects of intranasal naloxone in people with diabetes at risk for HAAF.

Permanent hypothyroidism following immune checkpoint inhibitors induced thyroiditis may be associated with improved survival: results of an exploratory study.

Background: Immune-related endocrinopathies are common after immune checkpoint inhibitor (ICI) therapy, among which destructive thyroiditis is the most prevalent. Improved survival outcomes have been associated with immune-related adverse events. We aimed to compare the clinical course and biochemical parameters of two subtypes of ICI-related destructive thyroiditis: a transient thyrotoxicosis that reverts to either euthyroidism (TT; transient thyroiditis) versus progression to permanent hypothyroidism (PH), and to identify prognostic markers in cancer patients receiving ICI therapy who developed DT. Methods: This retrospective observational study included 124 patients who developed a transient thyrotoxicosis due to a destructive thyroiditis after ICI therapy from January 1, 2016 to April 30, 2021 at the Montefiore Medical Center. Patients were categorized as either TT or PH based on spontaneous renormalization of the TSH or the permanent need for thyroid hormone replacement, respectively. Thyroid hormone and antibody levels, serum inflammatory markers, eosinophils, and metabolic uptake of the thyroid on PET imaging, each corresponding closest to a suppressed TSH, were characterized. Survival from TT and PH were also analyzed. Results: Of the 124 patients, 53 developed PH and 71 developed TT. The PH group developed thyrotoxicosis at a median of 42 days from the first ICI dose while the TT group took significantly longer at 56 days. Thyroidal PET uptake was increased in 18.9% of the PH group versus 6.0% of the TT group (P=0.04). Three different survival models consistently demonstrated a trend towards increased survival in the PH group, compared to the TT group. Conclusion: Our results suggest that PH developing after ICI-induced destructive thyroiditis may be associated with a more robust inflammatory and antitumor response to ICI therapy. The results suggests that PH may be a potential clinical predictor of improved survival.

An Atypical Form of Diabetes Among Individuals With Low BMI.

OBJECTIVE: Diabetes among individuals with low BMI (<19 kg/m2) has been recognized for >60 years as a prevalent entity in low- and middle-income countries (LMICs) and was formally classified as "malnutrition-related diabetes mellitus" by the World Health Organization (WHO) in 1985. Since the WHO withdrew this category in 1999, our objective was to define the metabolic characteristics of these individuals to establish that this is a distinct form of diabetes. RESEARCH DESIGN AND METHODS: State-of-the-art metabolic studies were used to characterize Indian individuals with "low BMI diabetes" (LD) in whom all known forms of diabetes were excluded by immunogenetic analysis. They were compared with demographically matched groups: a group with type 1 diabetes (T1D), a group with type 2 diabetes (T2D), and a group without diabetes. Insulin secretion was assessed by C-peptide deconvolution. Hepatic and peripheral insulin sensitivity were analyzed with stepped hyperinsulinemic-euglycemic pancreatic clamp studies. Hepatic and myocellular lipid contents were assessed with 1H-nuclear magnetic resonance spectroscopy. RESULTS: The total insulin secretory response was lower in the LD group in comparison with the lean group without diabetes and the T2D group. Endogenous glucose production was significantly lower in the LD group than the T2D group (mean ± SEM 0.50 ± 0.1 vs. 0.84 ± 0.1 mg/kg · min, respectively; P < 0.05). Glucose uptake was significantly higher in the LD group in comparison with the T2D group (10.1 ± 0.7 vs. 4.2 ± 0.5 mg/kg · min; P < 0.001). Visceral adipose tissue and hepatocellular lipids were significantly lower in LD than in T2D. CONCLUSIONS: These studies are the first to demonstrate that LD individuals in LMICs have a unique metabolic profile, suggesting that this is a distinct entity that warrants further investigation.

Pituitary Metastasis Presenting With Central Diabetes Insipidus and Panhypopituitarism.

OBJECTIVE: We report a case of pituitary metastasis (PM) presenting with acute anterior and posterior pituitary dysfunction following a two-decade-long oncologic course marked by disease progression. CASE REPORT: An elderly woman with a history of stage IIA invasive ductal carcinoma of the breast presented with confusion. Her laboratory evaluation was significant for panhypopituitarism and central diabetes insipidus, and magnetic resonance imaging findings were suggestive of PM. She was treated with hormone replacement, resulting in the reversal of her metabolic and cognitive derangements. DISCUSSION: PM is a rare complication of advanced malignancy. Although several malignancies may spread to the pituitary, the most common are breast cancer in women and lung cancer in men. Unlike pituitary adenomas, which predominantly involve the anterior pituitary, PM has a predilection for the posterior lobe and infundibulum due to direct access via systemic circulation. The clinical presentation of PM depends on the size of the metastatic deposit and other structures involved in the vicinity of the sella. Magnetic resonance imaging with gadolinium is the gold standard for the evaluation of sellar masses. The diagnosis of PM involves a thorough history, physical examination, biochemical evaluation of the hypothalamic-pituitary axis, and imaging studies. CONCLUSION: Metastatic involvement of the pituitary is a rare condition seen in <2% of resected pituitary masses. The clinical presentation is heterogeneous and can include headache, visual impairment, and panhypopituitarism. Unfortunately, the presence of PM portends a poor prognosis, and the median survival rate after diagnosis is 6 to 13.6 months.