Sodium-glucose cotransporter-2 inhibitors reduce blood pressure (BP) and renal and cardiovascular events in patients with type 2 diabetes through not fully elucidated mechanisms. Aim of this study was to investigate whether dapagliflozin is able to acutely modify systemic and renal vascular function, as well as putative mechanisms. Neuro-hormonal and vascular variables, together with 24 h diuresis, urinary sodium, glucose, isoprostanes and free-water clearance were assessed before and after a 2-day treatment with dapagliflozin 10 mg QD in sixteen type 2 diabetic patients; data were compared with those obtained in ten patients treated with hydrochlorothiazide 12.5 mg QD. Brachial artery endothelium-dependent and independent vasodilation (by flow-mediated dilation) and pulse wave velocity were assessed. Renal resistive index was obtained at rest and after glyceryl trinitrate administration. Differences were analysed by repeated measures ANOVA, considering treatment as between factor and time as within factor; Bonferroni post hoc comparison test was also used. Dapagliflozin decreased systolic BP and induced an increase in 24 h diuresis to a similar extent of hydrochlorothiazide; 24 h urinary glucose and serum magnesium were also increased. 24 h urinary sodium and fasting blood glucose were unchanged. Oxidative stress was reduced, as by a decline in urinary isoprostanes. Flow-mediated dilation was significantly increased (2.8 ± 2.2 to 4.0 ± 2.1%, p < 0.05), and pulse-wave-velocity was reduced (10.1 ± 1.6 to 8.9 ± 1.6 m/s, p < 0.05), even after correction for mean BP. Renal resistive index was reduced (0.62 ± 0.04 to 0.59 ± 0.05, p < 0.05). These vascular modifications were not observed in hydrochlorothiazide-treated individuals. An acute treatment with dapagliflozin significantly improves systemic endothelial function, arterial stiffness and renal resistive index; this effect is independent of changes in BP and occurs in the presence of stable natriuresis, suggesting a fast, direct beneficial effect on the vasculature, possibly mediated by oxidative stress reduction.

In type 2 diabetes, prevalence of nonalbuminuric renal impairment is increasing worldwide, though its clinical significance remains unclear. This large-cohort study aimed at evaluating the association of this phenotype with cardiovascular risk factors and other complications. Type 2 diabetic patients from the Renal Insufficiency And Cardiovascular Events (RIACE) Italian Multicenter Study (n = 15 773), visiting consecutively 19 hospital-based Diabetes Clinics in years 2007–2008, were examined. Serum creatinine was assessed by the Jaffe method; albuminuria was measured by immunonephelometry or immunoturbidimetry. Of patients with renal impairment, as identified by an estimated glomerular filtration rate (eGFR) less than 60 ml/min per 1.73 m2, 56.6% were normoalbuminuric, 30.8% were microalbuminuric, and 12.6% were macroalbuminuric. Percentages were similar when GFR was estimated using the more accurate Chronic Kidney Disease Epidemiology Collaboration equation instead of the simplified Modification of Diet in Renal Disease formula, and were independent of age, thus indicating that the increasing prevalence of this phenotype does not reflects misclassification of elderly patients. Nonalbuminuric renal impairment was not associated with HbA1c and correlated less strongly with retinopathy and hypertension than albuminuria, either alone or associated with reduced eGFR. It was associated with a higher prevalence of cardiovascular disease (CVD) than albuminuria alone, but lower than albuminuric renal impairment. Female sex correlated with nonalbuminuric renal impairment and male sex with the albuminuric forms. These data show that type 2 diabetic patients with nonalbuminuric renal impairment exhibit distinct clinical features, suggesting predominance of macroangiopathy as underlying renal pathology, and that this phenotype is associated with significant CVD burden.

We assessed the impact of vascular and perivascular tumour necrosis factor-alpha (TNF-α) on the endothelin (ET)-1/nitric oxide (NO) system and the molecular pathways involved in small arteries from visceral fat of obese patients (Obese) and Controls. Isolated small arteries from 16 Obese and 14 Controls were evaluated on a pressurized micromyograph. Endogenous ET-1 activity was assessed by the ET_A blocker BQ-123. TNF-α and NO were tested by anti-TNF-α infliximab (IFX) and N^ω-nitro-l-arginine methylester (L-NAME). Gene and protein expression of TNF-α, ET-1, ET_A, and ET_B receptors were determined by RT-PCR and IHC on arterial wall and in isolated adipocytes. Obese showed a blunted L-NAME-induced vasoconstriction, which was potentiated by IFX, and an increased relaxation to BQ-123, unaffected by L-NAME but attenuated by IFX. Perivascular adipose tissue (PVAT) removal reversed these effects. Obese showed intravascular superoxide excess, which was decreased by apocynin (NAD(P)H oxidase inhibitor), L-NAME, and BQ-123 incubations, and abolished by IFX. An increased vascular expression of ET-1, ET_A, and ET_B receptors, and higher vascular/perivascular TNF-α and TNF-α receptor expression were also detected. The arterial expression and phosphorylation of c-Jun N-terminal kinase (JNK) were higher in Obese vs. Controls, and downregulated by IFX. In small arteries of Obese, PVAT-derived TNF-α excess, and an increased vascular expression of ET-1 and ET_A receptor, contribute to the ET-1/NO system imbalance, by impairing tonic NO release. Reactive oxygen species excess, via NAD(P)H oxidase activation, induces the endothelial nitric oxide synthase uncoupling, which in turn generates superoxide and impairs NO production. The up-regulated JNK pathway represents a crucial molecular signalling involved in this process.

OBJECTIVE: To examine the association of hemoglobin (Hb) A1c variability with microvascular complications in the large cohort of subjects with type 2 diabetes from the Renal Insufficiency And Cardiovascular Events (RIACE) Italian Multicenter Study. RESEARCH DESIGN AND METHODS: Serial (3–5) HbA1c values collected in a 2-year period before enrollment were available from 8,260 subjects from 9 centers (of 15,773 patients from 19 centers). HbA1c variability was measured as the intraindividual SD of 4.52 ± 0.76 values. Diabetic retinopathy (DR) was assessed by dilated funduscopy. Chronic kidney disease (CKD) was defined based on albuminuria, as measured by immunonephelometry or immunoturbidimetry, and estimated glomerular filtration rate (eGFR) was calculated from serum creatinine. RESULTS: Median and interquartile range of average HbA1c (HbA1c-MEAN) and HbA1c-SD were 7.57% (6.86–8.38) and 0.46% (0.29–0.74), respectively. The highest prevalence of microalbuminuria, macroalbuminuria, reduced eGFR, albuminuric CKD phenotypes, and advanced DR was observed when both HbA1c parameters were above the median and the lowest when both were below the median. Logistic regression analyses showed that HbA1c-SD adds to HbA1c-MEAN as an independent correlate of microalbuminuria and stages 1–2 CKD and is an independent predictor of macroalbuminuria, reduced eGFR, and stages 3–5 albuminuric CKD, whereas HbA1c-MEAN is not. The opposite was found for DR, whereas neither HbA1c-MEAN nor HbA1c-SD affected nonalbuminuric CKD. CONCLUSIONS: In patients with type 2 diabetes, HbA1c variability affects (albuminuric) CKD more than average HbA1c, whereas only the latter parameter affects DR, thus suggesting a variable effect of these measures on microvascular complications.