Determining a Diagnostic Algorithm for Hyperinsulinaemia
Background: Ascertaining Kraft dynamic insulin response patterns following a 3-h 100 g oral glucose tolerance test seems to be the most reliable method for diagnosing hyperinsulinaemia. However, this test may be too resource-intensive for standard clinical use.
Aim: This study aims to see if Kraft patterns can be accurately predicted using fewer blood samples with sensitivity and specificity analyses.
Setting: St Joseph Hospital, Chicago, Illinois, United States and Human Potential Centre, Auckland University of technology, Auckland, New Zealand.
Method: We analysed the results of 4185 men and women with a normal glucose tolerance, who had a 100 g oral glucose tolerance test with Kraft pattern analysis. Participants were dichotomised into normal–low insulin tolerance (Kraft I or V patterns) or hyperinsulinaemia (Kraft IIA–IV patterns). Sensitivity and specificity analysis was applied to available variables (including age, body mass index, fasting insulin or glucose) both individually and in combination.
Results: Out of a maximal combined sensitivity and specificity score of 2.0, 2-h insulin level > 45 µU/mL attained the highest score (1.80). Two-hour insulin also attained the highest sensitivity (> 30 µU/mL, 0.98) and the highest specificity (> 50 µU/mL, 0.99) scores. Combining the 2-h insulin with other variables reduced the sensitivity and/or specificity. Dynamic measures had a better combined sensitivity and specificity compared to fasting or anthropological measures.
Conclusion: People with a 2-h plasma insulin level < 30 µU/mL are unlikely to be hyperinsulinaemic. Given that first-line treatment is lifestyle modification, we recommend that a 2-h plasma insulin level > 30 µU/mL following a 100 g oral glucose tolerance test be used to identify the hyperinsulinaemic individual.