Prediabetes is a significant metabolic status since there is high potential for future progression of diabetes mellitus (DM). People with prediabetes are at increased risk of cardiovascular disease (CVD) and mortality. Endothelial and microvascular dysfunction is considered a key step towards the development and progression of CVD. Importantly, endothelial and microvascular dysfunction can be detected and monitored using non-invasive procedures in peripheral organs and tissues, including the retina, kidney, skin and skeletal muscle. Structural and functional alterations of the microvasculature have been consistently documented in the above microvascular beds in patients with diabetes mellitus. In contrast, such alterations remain understudied in prediabetes, but are currently receiving attention as markers of subclinical and future CVD. The aim of this review is to summarize available evidence regarding the presence of subclinical microvascular and endothelial dysfunction in prediabetes and their impact on cardiovascular risk.

Objective: Existing data confirm the presence of microvascular dysfunction in hypertension and diabetes mellitus (DM). Prediabetes is recognized as a significant metabolic status, being a key factor in the occurrence of DM and there is increasing evidence concerning microvascular complications in prediabetes. Laser speckle contrast analysis (LASCA) is a non-invasive technique that can be used to evaluate skin microvascular function. The aim of our study was to assess cardiovascular factors that are possibly associated with microvascular reactivity in a population from normoglycaemia to DM. Design and method: Individuals with normoglycemia, prediabetes and diabetes without established cardiovascular disease were included in the study. In all participants, forearm skin blood flow was recorded under standardized conditions using a laser speckle contrast imager (PeriCam PSI NR System, Perimed). Post-occlusive reactive hyperaemia (PORH) was assessed following a standardized protocol and data were analyzed with a signal processing software (PIMSoft, Perimed). Skin microvascular reactivity was expressed as a percentage increase between baseline and peak perfusion (%). Office BP was measured in each participant according to a standard methodology and aortic blood pressure was assessed using the Sphygmocor device. Results: Fifty individuals (18 patients with prediabetes, 16 patients with DM and 16 controls) were included in the study. In the univariate model both glucose levels and aortic systolic blood pressure (aSBP) correlated inversely with microvascular reactivity (r = -0.382 and r = -0.349, p<0.01 for both comparisons) However, in the multivariate model only the association with aSBP remained statistically significant (beta = -0.363, p<0.05). Conclusions: Only central SBP, but not glucose predicted skin microvascular dysfunction in individuals with normoglycemia, prediabetes and diabetes and without established cardiovascular disease.