One-hour post-load plasma glucose and IGF-1 in hypertensive patients

In normoglucose-tolerant subjects (NGT), 1-h post-load plasma glucose value ≥155 mg/dL, during an oral glucose tolerance test (OGTT), is associated with an increased risk of type-2 diabetes (T2D) and subclinical organ damage. Insulin-like growth factor-1 (IGF-1) is involved in the pathogenesis of insulin resistance (IR) and T2D. Moreover, hypertensives have different degrees of IR and different levels of IGF-1. Actually, there are no data supporting the association between post-load glucose and IGF-1; thus, the aim of the study was to investigate this relationship.

We enrolled 1126 never-treated hypertensive subjects who underwent an OGTT and clinical characterization. Insulin sensitivity was assessed by the Matsuda index. IGF-1 was measured by a sensitive immunoradiometric assay.

Among participants, 764 had NGT, 263 had impaired glucose tolerance (IGT) and 99 had T2D. According to the 1-h post-load plasma glucose cut-off point of 155 mg/dL, we divided NGT subjects into NGT < 155 mg/dL and NGT ≥ 155 mg/dL. NGT ≥ 155 in comparison with NGT < 155 had significantly reduced insulin sensitivity and IGF-1 levels. At multiple regression analysis, IGF-1 was the major determinant of 1-h post-load glucose in NGT ≥ 155 subjects, IGT and diabetics, accounting for 20·9%, 17·7% and 15·5% of its variation in the respective models.

In hypertensive NGT ≥ 155 subjects, IGF-1 results strongly associated with 1-h post-load glucose, similarly to that observed in IGT and diabetics. This finding has clinical relevance because both low IGF-1 levels and 1-h post-load glucose in NGT subjects are associated with subclinical organ damage, an independent predictor of cardiovascular events.