GLYCEMIC RESPONSE TO STRESS IS ALTERED IN EUGLYCEMIC PIMA-INDIANS

The aim of this work was to study the effects of a computer-driven men tal arithmetic task on blood glucose in a group of four male and four female euglycemic Caucasians and a group of seven male and six female euglycemic Pima Indians. Approximately 60% of euglycemic Pima Indian N ative Americans eventually develop type 2 diabetes, while only 5% of C aucasians develop the disease. All subjects had normal glucose toleran ce. Subjects were given a standard breakfast; 2 h later, they were giv en a computerized mental arithmetic stress test for 10 min. Before, du ring and after the test, several variables were analyzed, including se rum concentrations of glucose, insulin, glucagon and plasma cortisol a nd catecholamines. Heart rate, systolic and diastolic blood pressure a nd all the stress hormones increased during stress and decreased durin g recovery in all subjects. Blood glucose consistently declined one ho ur after the meal in all subjects. However, while it continued to decl ine following stress in seven out of eight Caucasian subjects, it cons istently increased during and following stress in 10 out of 13 Pima In dians. Pasting serum glucose in Pima Indians and Caucasians was respec tively 5.07 + 0.08 mM and 5.04 + 0.09 mM. Two-hour post-prandial value s were 5.63 + 0.22 mM and 5.48 + 0.19 mM respectively, whereas post-st ress values were 6.15 + 0.19 mM for Pima Indians and 5.22 + 0.20 mM fo r Caucasians. Both serum glucose means following stress (t = 3.1, P < 0.005) and the direction of change in serum glucose in response to men tal arithmetic (chi(2) = 8.2, P < 0.01) clearly differentiated Pimas f rom Caucasians. These data suggest that abnormal glycemic responsivene ss to stress, even in the absence of impaired glucose tolerance, may b e present in subjects at high risk of developing diabetes and may ther efore be related in some way to the chain of events leading to the dev elopment of the disease.