Endocrine Abstracts

JOINT2892

Background: In our study, we aimed to show the role of insulin level obtained by oral glucose tolerance test (OGTT) and insulin resistance in indicating dysglycemia and their correlation with HbA1c level.

Material and methods: The data of the cases who administered OGTT in our clinic between 2014 and 2024 were examined retrospectively. For OGTT, 1. 75 g/kg (maximum 75 g) dextrose was administered perorally and serum glucose and insulin levels were measured at 0. and 120. minutes. Insulin resistance was defined in those with serum insulin level >75 mU/l at 120. minutes. Results were presented as mean±standard deviation or median (25-75p) depending on the normality of the distribution.

Results: Of the 512 patients included in the study [median age 13. 7 (12 – 15. 5) years], 53. 9% were female and 93. 9% were pubertal. When the OGTT results of the patients were examined, insulin resistance was detected in 58% (n = 297). While the HbA1c level didn’t show a significant difference when the cases were grouped according to obesity or insulin resistance (p>0. 05), it was significantly higher in those with impaired glucose tolerance (P < 0. 001). HOMA-IR, 0. and 120. minute insulin levels were found to be higher in obese patients, those with impaired glucose tolerance and those with insulin resistance than those without (P < 0. 05). Impaired glucose tolerance was detected in 8. 2% of the group with normal HbA1c. For the diagnosis of insulin resistance, when the basal insulin level is taken as 23. 4 mU/l; It was found to have 80% sensitivity and 74% specificity (AUC=0. 829, P < 0. 001). When the 0. minute HOMA-IR upper limit for the diagnosis of insulin resistance is taken as 5. 6; it was observed that it had 78% sensitivity and 73% specificity (AUC=0. 817, P < 0. 001), and when the 120th minute HOMA-IR upper limit was taken as 19, it had 96% sensitivity and 94% specificity (AUC=0. 985, P < 0. 001). There was no significant relationship between HbA1c and insulin levels at 0. or 120. minutes (p>0. 05).

Conclusion: In this study, we showed that the insulin level measured by OGTT isn’t guiding in the diagnosis of prediabetes. Additionally, we found that the upper limit of basal fasting serum insulin level, which is used for insulin resistance especially in the pubertal period, can be lowered to less than 30 mU/l, but HbA1c isn’t compatible with OGTT for the definition of insulin resistance. We evaluated that HOMA-IR can be used with high specificity and sensitivity in the definition of insulin resistance in children.