Longitudinal Changes in Insulin Resistance, Beta-Cell Function and Glucose Regulation Status in Prediabetes

The changes in insulin resistance and insulin secretion and their association with changes in glucose regulation status in Asians with prediabetes remain uncertain.

We included Korean adults (aged 20-79 years) with prediabetes who underwent routine medical check-ups at a mean interval of 5 years. Prediabetes was defined as fasting plasma glucose (FPG) 5.6-6.9mmol/l or HbA1c 5.7-6.4% (39-46mmol/mol). Insulin resistance (HOMA-IR) and beta-cell function (HOMA-%B) indices were assessed by homeostasis model assessment. Incident diabetes was defined as FPG ≥ 7.0mmol/l, HbA1c ≥ 6.5% (48mmol/mol), or initiation of antidiabetic medications.

Among the 7,208 participants with prediabetes, 4,410 (61.2%) remained as prediabetes (control group), 2,123 (29.5%) reverted to normal glucose regulation (regressors), and 675 (9.4%) progressed to type 2 diabetes (progressors) after 5 years. Compared with the control group, the progressors had higher baseline HOMA-IR (2.48 ± 1.45 versus 2.06 ± 1.20, P < 0.001), but similar baseline HOMA-%B (74.6 ± 47.6 versus 73.1 ± 41.4, P=0.68). By contrast, the regressors had lower baseline HOMA-IR (1.98 ± 1.14 versus 2.06 ± 1.20, P = 0.035) but higher baseline HOMA-%B (77.4 ± 43.1 versus 73.1 ± 41.4, P = 0.001). After 5 years, the progressors showed a 31% increase in HOMA-IR (2.48 ± 1.45 versus 3.24 ± 2.10, P < 0.001) and 15% decrease in HOMA-%B (74.6 ± 47.6 versus 63.8 ± 40.4, P < 0.001), whereas the regressors showed 29% decrease in HOMA-IR (1.98 ± 1.14 versus 1.41 ± 0.78, P < 0.001) and 4% increase in HOMA-%B (77.4 ± 43.1 versus 80.2 ± 47.9, P = 0.010).

Although increase in insulin resistance and decrease in beta-cell function both contributed to the progression to type 2 diabetes from prediabetes, longitudinal change in insulin resistance was the predominant factor in Koreans.