BackgroundEffects of major dietary macronutrients on glucose-insulin homeostasis remain controversial and may vary by the clinical measures examined. We aimed to assess how saturated fat (SFA), monounsaturated fat (MUFA), polyunsaturated fat (PUFA), and carbohydrate affect key metrics of glucose-insulin homeostasis.Methods and FindingsWe systematically searched multiple databases (PubMed, EMBASE, OVID, BIOSIS, Web-of-Knowledge, CAB, CINAHL, Cochrane Library, SIGLE, Faculty1000) for randomised controlled feeding trials published by 26 Nov 2015 that tested effects of macronutrient intake on blood glucose, insulin, HbA1c, insulin sensitivity, and insulin secretion in adults aged ≥18 years. We excluded trials with non-isocaloric comparisons and trials providing dietary advice or supplements rather than meals. Studies were reviewed and data extracted independently in duplicate. Among 6,124 abstracts, 102 trials, including 239 diet arms and 4,220 adults, met eligibility requirements. Using multiple-treatment meta-regression, we estimated dose-response effects of isocaloric replacements between SFA, MUFA, PUFA, and carbohydrate, adjusted for protein, trans fat, and dietary fibre. Replacing 5% energy from carbohydrate with SFA had no significant effect on fasting glucose (+0.02 mmol/L, 95% CI = -0.01, +0.04; n trials = 99), but lowered fasting insulin (-1.1 pmol/L; -1.7, -0.5; n = 90). Replacing carbohydrate with MUFA lowered HbA1c (-0.09%; -0.12, -0.05; n = 23), 2 h post-challenge insulin (-20.3 pmol/L; -32.2, -8.4; n = 11), and homeostasis model assessment for insulin resistance (HOMA-IR) (-2.4%; -4.6, -0.3; n = 30). Replacing carbohydrate with PUFA significantly lowered HbA1c (-0.11%; -0.17, -0.05) and fasting insulin (-1.6 pmol/L; -2.8, -0.4). Replacing SFA with PUFA significantly lowered glucose, HbA1c, C-peptide, and HOMA. Based on gold-standard acute insulin response in ten trials, PUFA significantly improved insulin secretion capacity (+0.5 pmol/L/min; 0.2, 0.8) whether replacing carbohydrate, SFA, or even MUFA. No significant effects of any macronutrient replacements were observed for 2 h post-challenge glucose or insulin sensitivity (minimal-model index). Limitations included a small number of trials for some outcomes and potential issues of blinding, compliance, generalisability, heterogeneity due to unmeasured factors, and publication bias.ConclusionsThis meta-analysis of randomised controlled feeding trials provides evidence that dietary macronutrients have diverse effects on glucose-insulin homeostasis. In comparison to carbohydrate, SFA, or MUFA, most consistent favourable effects were seen with PUFA, which was linked to improved glycaemia, insulin resistance, and insulin secretion capacity.

White matter hyperintensities (WMH) in elderly individuals with vascular diseases are presumed to be due to ischemic small vessel diseases; however, their etiology is unknown. We examined the cross-sectional relationship between cerebrovascular hemodynamics and white matter structural integrity in elderly individuals with vascular risk factors. White matter hyperintensity volumes, fractional anisotropy (FA), and mean diffusivity (MD) were obtained from MRI in 48 subjects (75±7years). Pulsatility index (PI) and dynamic cerebral autoregulation (dCA) was assessed using transcranial Doppler ultrasound of the middle cerebral artery. Dynamic cerebral autoregulation was calculated from transfer function analysis (phase and gain) of spontaneous blood pressure and flow velocity oscillations in the low (LF, 0.03 to 0.15 Hz) and high (HF, 0.16 to 0.5 Hz) frequency ranges. Higher PI was associated with greater WMH (P<0.005). Higher phase across all frequency ranges was associated with greater FA and lower MD (P<0.005). Lower gain was associated with higher FA in the LF range (P=0.001). These relationships between phase and FA were significant in the territories limited to the middle cerebral artery as well as across the entire brain. Our results show a strong relationship between impaired cerebrovascular hemodynamics (PI and dCA) and loss of cerebral white matter structural integrity (WMH and DTI metrics) in elderly individuals.

ObjectiveTo test the hypothesis that racial-, age- and sex-specific incidence of cerebral venous thrombosis (CVT) has increased in the United States over the last decade.MethodsIn this retrospective cohort study, validated International Classification of Disease codes were used to identify all new cases of CVT (n = 5,567) in the State Inpatients Database (SID) of New York and Florida (2006–2016). A new CVT case was defined as first hospitalization for CVT in the SID without prior CVT hospitalization. CVT counts were combined with annual Census data to compute incidence. Joinpoint regression was used to evaluate trends in incidence over time.ResultsFrom 2006 to 2016, annual age and sex-standardized incidence of CVT in cases/million population ranged from 13.9 to 20.2, but incidence varied significantly by sex (females: 20.3–26.9; males 6.8–16.8) and by age/sex (females 18–44 yo: 24.0%–32.6%; males: 18–44 yo: 5.3–12.8). Incidence also differed by race (Blacks: 18.6–27.2; Whites: 14.3–18.5; Asians: 5.1–13.8). On joinpoint regression, incidence increased across 2006–2016 but most of this increase was driven by increase in all age groups of males (combined annualized percentage change [APC] 9.2%, p-value <0.001), females 45–64 yo (APC 7.8%, p-value <0.001) and females ≥65 yo (APC 7.4%, p-value <0.001). Incidence in females 18–44 yo remained unchanged over time.ConclusionCVT incidence is disproportionately higher in blacks compared to other races. New CVT hospitalizations increased significantly over the last decade mainly in males and older females. Further studies are needed to determine whether this increase represents true increase from changing risk factors or artefactual increase from improved detection.