title: Hypoglycemic counterregulatory responses differ between men and women with type 1 diabetes.
abstract: The aim of this study was to determine whether sex-related differences occur in counterregulatory responses to hypoglycemia in adult type 1 diabetic patients. Experiments were carried out on 16 (8 men/8 women) type 1 diabetic patients and compared with 16 (8 men/8 women) age- and weight-matched normal individuals. Men and women with type 1 diabetes were matched for age (26+/-2 vs. 25+/-1 years), duration of diabetes (9+/-1 vs. 8+/-1 years), glycemic control (HbA1c 7.7+/-0.3 vs. 7.8+/-0.2%), and weight (BMI 22.8+/-1 vs. 22.1+/-1 kg/m2), respectively. After normalizing plasma glucose overnight, patients underwent a 2-h hyperinsulinemic-hypoglycemic clamp study. Plasma glucose (3.0+/-0.1 mmol/l) and insulin (510+/-48 pmol/l) levels were equated in all groups. Plasma epinephrine, norepinephrine, growth hormone (GH), muscle sympathetic nerve activity (MSNA), and endogenous glucose production (EGP) responses were significantly lower (P<0.01) in type 1 diabetic women compared with men. Autonomic symptom scores, lipid oxidation, nonesterified fatty acids (NEFAs), and glycerol responses were equivalent between men and women with type 1 diabetes despite significantly reduced sympathoadrenal and MSNA responses in women. Autonomic nervous system (ANS) and EGP responses were equivalent in type 1 diabetic and normal individuals. However, lipid oxidation (assessed by indirect calorimetry), glycerol, and NEFA responses were increased (P<0.01) in type 1 diabetic patients compared with normal control subjects. We conclude that counterregulatory responses to fixed hypoglycemia differ markedly in men and women with type 1 diabetes: 1) sympathetic nervous system, GH, and EGP responses are significantly reduced in type 1 diabetic women, 2) autonomic symptom awareness and lipolytic responses appear to be relatively increased in type 1 diabetic women compared with men, and 3) during conditions of similar hyperinsulinemic hypoglycemia and ANS drive, lipid oxidation and lipolytic responses can be increased in type 1 diabetic patients compared with normal individuals.
authors.affiliation: Department of Medicine, Vanderbilt University School of Medicine and Veterans Administration Medical Center, Nashville, Tennessee 37232, USA. steve.davis@mcmail.vanderbilt.edu
authors.forename: S N
authors.initials: SN
authors.lastname: Davis
authors.forename: S
authors.initials: S
authors.lastname: Fowler
authors.forename: F
authors.initials: F
authors.lastname: Costa
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D002319:Cardiovascular System / Q000503:physiopathology; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D006728:Hormones / Q000097:blood; D006801:Humans; D007003:Hypoglycemia / Q000097:blood / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D008297:Male; D009132:Muscles / Q000294:innervation; D009490:Neurosecretory Systems / Q000378:metabolism; D012727:Sex Characteristics; D013564:Sympathetic Nervous System / Q000503:physiopathology
chemical_list: D001786:Blood Glucose; D006728:Hormones; D007328:Insulin