Relationship of insulin resistance to macro- and microvasculature reactivity in hypertension

Endothelial function in patients with newly diagnosed type 2 diabetes receiving early intensive insulin therapy

BACKGROUND

Multifactorial intervention is unable to improve endothelial dysfunction/cardiovascular outcome in type 2 diabetes. Intensive insulin therapy improves pancreatic β-cell dysfunction in patients with early stage diabetes. We investigated the effect of intensive insulin therapy on endothelial dysfunction in these patients.

METHODS

One hundred and sixteen patients with newly diagnosed type 2 diabetes and 59 healthy subjects received flow-mediated dilatation (FMD) and von Willebrand factor (vWF) measurement. Diabetic patients were further treated with either multifactorial intervention (group A), or intensive insulin therapy (group B) for 2 weeks. Both FMD and vWF measurement were repeated at the same time. FMD was reassessed 90 days after intervention.

RESULTS

Compared with healthy subjects, FMD in diabetic patients was significantly lower (group A: 15.99 ± 7.81 % vs. 25.17 ± 7.12 %, P < 0.01; group B: 16.85 ± 7.30 % vs. 25.17 ± 7.12%, P < 0.01), plasma vWF was significantly higher (group A: 224.34 ± 7.36 U/l vs. 109.69 ± 6.30 U/l, P < 0.01; group B: 219.18 ± 6.92 U/l vs. 109.69 ± 6.30 U/l, P < 0.01). After treatment, there was no significant change of FMD in either group. The vWF did not change after multifactorial intervention (220.96 ± 6.85 U/l vs. 224.34 ± 7.36 U/l, P = 0.49), but significantly decreased after intensive insulin therapy (155.08 ± 11.82 U/l vs. 219.18 ± 6.92 U/l, P = 0.0013).

CONCLUSIONS

Intensive insulin therapy significantly improves endothelial injury/dysfunction as measured by vWF in early stage type 2 diabetes. Further study is needed to determine whether plasma vWF can help early identification, stratification and management of diabetic endothelial dysfunction.

Association between diabetic retinopathy and flow-mediated vasodilation in type 2 DM

OBJECTIVE

Retinal endothelial dysfunction is a key in the etiogenesis of diabetic retinopathy (DR), in patients with type 2 diabetes mellitus (DM). Brachial artery flow-mediated vasodilation (FMD) is a marker of endothelial function associated with production of endogenous nitric oxide. Using FMD, we investigated the relationship between macrovascular function and DR.

METHODS

We studied 74 patients with type 2 DM, including non-DR (NDR) (n = 30); mild nonproliferative DR (NPDR) (n = 16); moderate NPDR (n = 10); severe NPDR (n = 10); and proliferative DR (PDR) (n = 8); and 21 age-matched controls. We measured FMD in each group. Retinal blood flow and pulsatility ratios were measured using laser Doppler velocimetry.

RESULTS

FMD decreased significantly in patients with DM compared with healthy control subjects. No significant differences were found in FMD among the NDR, mild NPDR, and moderate NPDR groups. FMD decreased significantly in the severe NPDR and PDR groups compared with the NDR group. FMD was significantly and negatively correlated with duration of DM and pulsatility ratio.

CONCLUSION

Systemic endothelial dysfunction appears to be associated with DR and vascular abnormalities in patients with type 2 DM.

Maternal high-fat diet impacts endothelial function in nonhuman primate offspring

OBJECTIVE:

The link between maternal under-nutrition and cardiovascular disease (CVD) in the offspring later in life is well recognized, but the impact of maternal over-nutrition on the offspring's cardiovascular function and subsequent risk for CVD later in life remains unclear. Here, we investigated the impact of maternal exposure to a high-fat/calorie diet (HFD) during pregnancy and early postnatal period on endothelial function of the offspring in a nonhuman primate model.

METHODS:

Offspring, naturally born to either a control (CTR) diet (14% fat calories) or a HFD (36% fat calories) consumption dam, were breast-fed until weaning at about 8 months of age. After weaning, the offspring were either maintained on the same diet (CTR/CTR, HFD/HFD), or underwent a diet switch (CTR/HFD, HFD/CTR). Blood samples and arterial tissues were collected at necropsy when the animals were about 13 months of age.

RESULTS:

HFD/HFD juveniles displayed an increased plasma insulin level and glucose-stimulated insulin secretion in comparison with CTR/CTR. In abdominal aorta, but not the renal artery, acetylcholine-induced vasorelaxation was decreased remarkably for HFD/HFD juveniles compared with CTR/CTR. HFD/HFD animals also showed a thicker intima wall and an abnormal vascular-morphology, concurrent with elevated expression levels of several markers related to vascular inflammation and fibrinolytic function. Diet-switching animals (HFD/CTR and CTR/HFD) displayed modest damage on the abdominal vessel.

CONCLUSION:

Our data indicate that maternal HFD exposure impairs offspring's endothelial function. Both early programming events and postweaning diet contribute to the abnormalities that could be reversed partially by diet intervention.