Individuals with impaired glucose tolerance or impaired fasting glucose are at high risk of developing type 2 diabetes and cardiovascular diseases (1). Identifying those individuals whose glucose tolerance status (GTS) will deteriorate over the years would be of public health importance, due to its preventive implications.

We assessed the metabolic syndrome and lifestyle habits as predictors of 23-year GTS deterioration among survivors of a nationwide longitudinal study (the Israeli Glucose Intolerance, Obesity and Hypertension Study) subsample (2). The study was approved by the institutional review board, and all subjects gave written informed consent. Among the 562 nondiabetic subjects at baseline to whom either oral glucose tolerance test or fasting glucose were available at follow-up (298 male and 264 female subjects, mean age 70.4 ± 6.8 years), 54.6% deteriorated (i.e., they were normoglycemic at baseline and became impaired or diabetic at follow-up or were impaired and became diabetic). Male subjects experienced higher deterioration rates (59.4%) than female subjects (49.2%) (P = 0.02). Among the ethnic groups, North African–born subjects had the highest rates of deterioration and European/American-born subjects the lowest (67.4 and 47.1%, respectively; P = 0.01). Those who have ever smoked cigarettes and sedentary individuals exhibited higher deterioration rates than those who have never smoked and those currently physically active (58.6 vs. 50.9%, P = 0.06 for smoking and 59.7 vs. 50.6%, P = 0.03 for physical activity, respectively). All metabolic syndrome components other than HDL cholesterol were found to be significantly associated to deterioration. In multiple logistic regression analysis, subjects with the metabolic syndrome had a sex-, age-, ethnic origin–, smoking-, and physical activity–adjusted 3.09 increased risk for GTS deterioration (95% CI 1.67–5.72; C index = 0.65).

In the study, an increasing number of metabolic syndrome components were significantly associated with increasing rates of deterioration in GTS from 43.2% among those who had none of the components to almost 90% in those who had four or five components (P < 0.001).

Presence of the metabolic syndrome at baseline was found to predict both the deterioration in GTS, a smoldering process on the axis of time, and diabetes incidence. When evaluating its predictive value in detecting type 2 diabetes or GTS deterioration, one must relate to the paradigm of fasting blood glucose being a component of both the outcome and the metabolic syndrome. Our study exhibited similar results, with metabolic syndrome not including fasting blood glucose (odds ratio for deterioration of those positive for metabolic syndrome 2.22 [95% CI 1.19–4.11]). Assuming that those who did not survive were subjects with the less-favorable health status, these results are most likely underestimated. Modifiable lifestyle characteristics were found to predict 23-year GTS deterioration in order to facilitate the prevention or delay of type 2 diabetes.

This study was supported by a grant from Israeli Chief Scientist of the Ministry for Health and the Israeli Diabetes Association.

Lorenzo C, Okoloise M, William K, Stern MP, Haffner SM: The metabolic syndrome as predictor of type 2 diabetes: the San Antonio Heart Study.
Diabetes Care
Modan M, Halkin H, Almog S, Lusky A, Eshkol A, Shefi M, Shitrit A, Fuchs Z: Hyperinsulinemia: a link between hypertension, obesity and glucose intolerance.
J Clin Invest