Aims/hypothesis: Lack of reversal of prediabetes (impaired glucose tolerance and/or impaired fasting glucose) to normal glucose regulation (NGR) during a lifestyle intervention is strongly associated with a higher incidence of diabetes later in life. In the Tübingen Lifestyle Intervention Program (TULIP) we hypothesised that an at-risk phenotype may exist at baseline that associates with this nonresponse to the intervention.
Methods: A total of 120 participants of TULIP with prediabetes at baseline were studied. Participants underwent 9 months of lifestyle intervention and had measurements of insulin secretion and insulin sensitivity during a 75 g OGTT, and measurements of liver fat content by proton magnetic resonance spectroscopy.
Results: During the lifestyle intervention, 55% of the participants did not revert to NGR. Even among participants with the largest body fat loss (upper quartile: -6.9 ± 3.3%, mean ± SD), 40% did not revert to NGR. In this regard, we identified at baseline a high-risk phenotype (n = 72) consisting of low disposition index or low insulin sensitivity + nonalcoholic fatty liver disease (NAFLD) and a low-risk phenotype (n = 48, all other traits). While the adjusted decrease in body fat was almost identical between these phenotypes (-5.7 ± 15.3% vs -7.7 ± 15.2%, p = 0.49), the high-risk phenotype had a smaller decrease in adjusted 2 h blood glucose levels (-3.7 ± 20.3% vs -18.5 ± 20.0%, p = 0.0009). In addition, only 31% of the participants with the high-risk phenotype, but 67% with the low-risk phenotype, reverted to NGR (p < 0.0001). The odds ratio for reaching the status NGR was 4.54 (95% CI 2.08, 9.94) for participants having the low-risk phenotype.
Conclusions/interpretation: Stratification of individuals with prediabetes at baseline into a high-risk and a low-risk phenotype, based on corrected insulin secretion and insulin-resistant NAFLD, may help to determine the effectiveness of a lifestyle intervention to revert individuals to NGR.
Keywords: Impaired glucose tolerance; Insulin secretion; Insulin sensitivity; Lifestyle intervention; Nonalcoholic fatty liver disease; Normal glucose regulation; Prediabetes.