H and ex vivo2 H magnetic resonance spectroscopy before and during hyperinsulinemiceuglycemic clamps with isotope dilution. Mice underwent identical clamp procedures and hepatic transcriptome analyses.RESULTS. PO administration decreased whole-body, hepatic, and adipose tissue insulin sensitivity by 25%, 15%, and 34%, respectively. Hepatic triglyceride and ATP content rose by 35% and 16%, respectively. Hepatic gluconeogenesis increased by 70%, and net glycogenolysis declined by 20%. Mouse transcriptomics revealed that PO differentially regulates predicted upstream regulators and pathways, including LPS, members of the TLR and PPAR families, NF-κB, and TNF-related weak inducer of apoptosis (TWEAK). CONCLUSION.Saturated fat ingestion rapidly increases hepatic lipid storage, energy metabolism, and insulin resistance. This is accompanied by regulation of hepatic gene expression and signaling that may contribute to development of NAFLD. PO results in increased circulating TG, glucagon, and incretins. After PO administration, TG in plasma rose by 59% (area under the time curve [AUC], P < 0.001) and by 156% in chylomicrons (AUC, P = 0.009) (Figure 2A). The AUC for plasma free fatty acids (FFA) ( Figure 2B) and insulin concentrations ( Figure 2C) was unchanged, while the AUC for plasma C-peptide was 28% higher after PO ingestion versus VCL (P < 0.005, Figure 2D). Of note, FFA were increased at 300, 420, and 480 minutes. Blood glucose levels were not different between PO-and VCL-treated groups ( Figure 2E). Plasma glucagon rose by 41% (AUC, P < 0.0001) only after PO ingestion ( Figure 2F). Also, glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP) levels were markedly increased and remained elevated after PO ingestion (both P < 0.005) (Supplemental Figure 2; supplemental material available online with this article; https://doi.org/10.1172/ JCI89444DS1). Circulating levels of TNF-α, IL-6, fetuin-A, chemerin, omentin, and cortisol were not different between PO and VCL groups (P > 0.5 for all) (Supplemental Table 1). REGISTRATION. The Journal of Clinical Investigation C L I N I C A L M E D I C I N EPO induces insulin resistance at whole-body, liver, and adipose tissue levels. Insulin sensitivity was measured using hyperinsulinemic-euglycemic clamp tests in healthy humans. Steady state was reached (Supplemental Figure 1), and pertinent parameters were analyzed during this time. PO ingestion reduced WBIS by 25% compared with VCL treatment (P = 0.0005, Figure 3A). Furthermore, after PO, volunteers also showed a decrease of 22% (P = 0.002) in the rate of glucose disappearance (Rd), mostly due to a 33% (P = 0.01) reduction in glucose oxidation (GOX), while the rate of nonoxidative glucose disposal remained unchanged

Fasting hyperglycemia is due to excessive glucose production in people with either IFG/NGT or IFG/IGT. Both insulin action and postprandial glucose concentrations are normal in IFG/NGT but abnormal in IFG/IGT. This finding suggests that hepatic and extrahepatic insulin resistance causes or exacerbates postprandial glucose intolerance in IFG/IGT. Elevated gluconeogenesis in the fasting state in IFG/NGT and impaired insulin-induced suppression of both gluconeogenesis and glycogenolysis in IFG/IGT suggest that alteration in the regulation of these pathways occurs early in the evolution of type 2 diabetes.

The contributions of hepatic glycogenolysis to fasting glucose production and direct pathway to hepatic glycogen synthesis were quantified in eight type 1 diabetic patients and nine healthy control subjects by ingestion of 2 H 2 O and acetaminophen before breakfast followed by analysis of urinary water and acetaminophen glucuronide. After overnight fasting, enrichment of glucuronide position 5 relative to body water (G5/body water) was significantly higher in type 1 diabetic patients compared with control subjects, indicating a reduced contribution of glycogenolysis to glucose production (38 ؎ 3 vs. 46 ؎ 2%). Following breakfast, G5/body water was significantly higher in type 1 diabetic patients, indicating a smaller direct pathway contribution to glycogen synthesis (47 ؎ 2 vs. 59 ؎ 2%). Glucuronide hydrogen 2 enrichment (G2) was equivalent to body water during fasting (G2/body water 0.94 ؎ 0.03 and 1.02 ؎ 0.06 for control and type 1 diabetic subjects, respectively) but was significantly lower after breakfast (G2/body water 0.78 ؎ 0.03 and 0.82 ؎ 0.05 for control and type 1 diabetic subjects, respectively). The reduced postprandial G2 levels reflect incomplete glucose-6-phosphate-fructose-6-phosphate exchange or glycogen synthesis from dietary galactose. Unlike current measurements of human hepatic glycogen metabolism, the 2 H 2 O/acetaminophen assay does not require specialized on-site clinical equipment or personnel. Diabetes

This paper reports the first application of high-resolution 1 H NMR spectroscopy to the plasma of five juveniles with glycogen storage disease type 1a (GSD1a), permitting the characterisation of the plasma metabolic profile and the identification of alterations relative to a set of control samples. The relaxation-weighted spectra allowed changes in low molecular weight compounds to be detected more clearly, whereas diffusion-edited spectra were used to characterise the plasma lipoprotein profile. Low molecular weight metabolites with altered levels in most patients were lactate, ketone bodies, acetate, creatine/creatinine and glucose. One of the patients showed distinctively lower glucose levels and higher lactate and ketone body contents, suggesting poorer metabolic control of the disease compared with other patients. In addition, a metabolite tentatively identified as a-hydroxyisobutyrate was only detected in the spectra of GSD1a plasmas, representing, therefore, a possible novel GSD1a biomarker. Total lipoprotein contents were higher in the plasma from GSD1a patients. Furthermore, lower HDL and higher VLDL þ LDL levels also characterised the plasma of these patients. Preliminary results on principal component analysis of 1 H NMR spectra allowed a clear separation between GSD1a and control plasmas. The specificity of the changes observed to GSD1a is discussed, together with the recognised potential of NMR and pattern recognition methods for aiding the diagnosis of GSD1a.

Plasma glucose, insulin and glucose tolerance were quantified in diabetic Goto-Kakizaki (GK) rats (342+/-45 g, n = 5) and compared with weight-matched non-diabetic Wistars (307+/-30 g, n = 8). Compared to Wistars, GK rats had higher fasting plasma insulin (219+/-50 versus 44+/-14 pmol/l, P<0.002) and glucose (9.2+/-2.3 versus 5.5+/-0.5 mmol/l, P<0.025). GK rats showed impaired glucose tolerance (IPGTT 2 h plasma glucose=14+/-1.5 versus 6.4+/-0.1 mmol/l, P<0.001). Endogenous glucose production (EGP) from glycogenolysis, phosphoenolpyruvate (PEP) and glycerol after 6 hours of fasting was quantified by a primed infusion of [U-(13)C]glucose and (2)H(2)O tracers and (2)H/(13)C NMR analysis of plasma glucose. EGP was higher in GK compared to Wistar rats (191+/-16 versus 104+/-27 mumol/kg per min, P<0.005). This was sustained by increased gluconeogenesis from PEP (85+/-12 versus 35+/-4 mumol/kg per min, P<0.02). Gluconeogenesis from glycerol was not different (20+/-3 in Wistar versus 30+/-6 mumol/kg per min for GK), and glycogenolysis fluxes were also not significantly different (76+/-23 mumol/kg per min for GK versus 52+/-19 mumol/kg per min for Wistar). The Cori cycle accounted for most of PEP gluconeogenesis in both Wistar and GK rats (85+/-15% and 77+/-10%, respectively). Therefore, increased gluconeogenesis in GK rats is largely sustained by increased Cori cycling while the maintenance of glycogenolysis indicates a failure in hepatic autoregulation of EGP.