Changes And Follow-up Of Insulin Phase 1 Secretion In Hyperthyroidism Complicated With Abnormal Glucose Metabolism

OBJECTIVE:To understand the islet function in patients with hyperthyroidism complicated with abnormal glucose metabolism,especially the function of insulin phase 1 secretion,to further verify the difference of phase 1 insulin secretion function between hyperthyroidism with abnormal glucose metabolism and T2DM,and to follow up the patients with hyperthyroidism complicated with abnormal glucose metabolism to explore the relationship between insulin phase 1 secretion function and blood glucose recovery after thyroid function control.METHODS:A total of 137 patients（67 males and 70 females）with hyperthyroidism treated in the first affiliated Hospital of Guangxi Medical University from January 2011 to October 2019 were selected as subjects,and115 patients with NGT,IGR and T2DM were collected as control group（71males and 44 females）.Grouping:（1）according to the results of OGTT test,the hyperthyroidism group was divided into three groups:hyperthyroidism with diabetes,（HDM）;hyperthyroidism patients with impaired glucose regulation,（HIGR）;hyperthyroidism patients with normal glucose tolerance（（HNGT））.（2）the control group was divided into two groups:type 2 diabetic group（T2DM）,impaired glucose regulation group,（IGR）;normal glucose tolerance group,（NGT）group.（3）patients with hyperthyroidism complicated with abnormal glucose metabolism（including HDM and HIGR）were followed up,and the follow-up group was divided into two groups according to whether the increased multiple of insulin（I_p/I₀）was less than 5:1group,decreased insulin phase 1 secretion function group（I_p/I₀<5）,insulin phase 1 secretion function normal group（I_p/I₀>5）.Data collection:the clinical data of all subjects,including sex,age,height,weight,thyroid function,blood lipids,etc,were collected,and oral glucose tolerance test（OGTT）and intravenous glucose tolerance test（IVGTT）were performed.The thyroid function and blood glucose were collected from the follow-up group.Evaluation index:in OGTT,insulin resistance was evaluated by HOMA-IR（insulin resistance index）,isletβcell secretion function was evaluated by HOMA-β（insulin secretion function index）and MBCI（modified isletβcell function index）.The insulin secretion function of phase2 was evaluated by I_P/I₀（multiple of insulin increase）,AUCins-_OGTT/AUCglu_-OGTT（area under insulin curve/area under blood glucose curve）and AUCins_-OGTT（area under insulin curve）.In IVGTT,I_p/I₀（multiple of insulin peak increase）,AUCins_-IVGTT（area under insulin curve）and AIR_0’¹0’（acute phase insulin secretion）were used to evaluate the function of insulin phase 1 secretion.RESULTS:1.The age of HDM and T2DM groups was higher than that of their respective NGT groups,and the BMI,TC and LDL-C of each subgroup of hyperthyroidism were lower than those of the control subgroups.The TG of HDM group was lower than that of T2DM group.2.In OGTT,the proportion of peak disappearance and delay in HDM group and T2DM group was higher than that in NGT and IGR groups,but there was no significant difference between HDM group and T2DM group（P>0.05）.The I_Pvalue of T2DM group was lower than that of NGT and IGR groups.The levels of I_Pand I_p/I₀in HDM group were higher than those in T2DM group,but there was no significant difference.The values of HOMA-βand AUCins-_OGTT/AUCglu_-OGTTin HDM and T2DM groups were lower than those in NGT and IGR groups,MBCI in HDM group was lower than that in HNGT group in hyperthyroidism group,and MBCI in T2DM and IGR groups was lower than that in NGT group in control group.There was no significant difference in I_P,I_P/I₀,AUCins_-OGTT/AUCglu_-OGTTand AUCins_-OGTTbetween HDM group and T2DM group.3.In IVGTT:among all groups,only T2DM group had no obvious peak of phase 1 secretion curve,and the other five groups had peak insulin secretion in 2～4min,while the curve of phase 1secretion in HDM group was higher than that in T2DM group,but lower than that in other groups.The values of I_p,I_p/I₀,AIR_0’¹0’and AUCins_-IVGTTin HDM group were significantly higher than those in T2DM group（P<0.05mm）.The values of I_p,I_p/I₀,AIR_0’¹0’and AUCins_-IVGTTin T2DM group were lower than those in NGT and IGR groups,and the difference was statistically significant.4.Follow-up:in the group with normal insulin phase1 secretion function,when the hyperthyroidism was controlled,the proportion of the group with normal,improved and no significant change of blood glucose was 74.2%,9.7%and 16.1%,respectively.The proportion of the group with normal blood glucose was significantly higher than that of the group with no significant change in blood glucose,and the difference was statistically significant（P<0.05）.In the group with normal phase 1 secretion,there was no deterioration of blood glucose after the control of hyperthyroidism.in the decreased phase 1 secretion group,when the hyperthyroidism was controlled,the blood glucose of the patients did not return to normal or improved.There is even a deterioration of blood sugar.CONCLUSIONS:The function of insulin phase 1 secretion in patients with hyperthyroidism with secondary diabetes is better than that in patients with hyperthyroidism with type 2 diabetes.It is suggested that I_p/I₀in IVGTT can be used to distinguish between them.