Figure 1.
Overview of the study design of Study 1.
356 subjects were analyzed by MxP™ Broad Profiling and MxP™ Eicosanoid analysis. From this total population, samples from 124 subjects which were collected and stored prior type-2 diabetes diagnosis were analyzed. In addition, OGTTt = 0 and OGTTt = 120 samples of a subgroup of 51 healthy and 47 diabetic subjects were analyzed by single ion monitoring.
Table 1.
Metabolite panel altered in type 2 diabetes.
Table 2.
Metabolites altered in non-fasted subjects prior to diabetes diagnosis and in pre-diabetic subjects.
Table 3.
Metabolites showing a difference in diabetic and healthy subjects at OGTT time-point 0 vs. 120.
Figure 2.
Hexosamine and branched-chain-amino acid levels differ between diabetic and healthy subjects at OGTTt = 0 vs. OGTTt = 120.
Depicted are boxplots of metabolite levels. Samples collected at OGTTt = 0 and OGTTt = 120 were measured with single ion monitoring. Study participants were categorized as diabetics (n = 47) or controls (n = 51) based on FPG and/or OGTTt = 120 levels. P-values for the difference between control and diabetic subjetcs at OGTT time point 0 vs. 120 are 6.84E-05 for fructosamine and 6.22E-06 for ketoisoleucine.
Figure 3.
Other than glucose, glyoxylate levels are strongly increased in a defined subgroup of diabetic patients.
Scatter plots of glucose and glyoxylate levels show an increase of glyoxlate during hyperglycemic stress (OGTTt = 120) which was observed to be stronger in a specific subgroup of diabetic patients with a history of anti-hypertensive medication intake. For glucose, no such specific increase in diabetic patients with a history of taking anti-hypertensive medication was seen. Subjects with anti-hypertension medication (med) are represented by circles; subjects with no history of anti-hypertensive medication (no med) are represented by crosses. Study participants were categorized as type-2 diabetics (n = 47) or control (n = 51) based on FPG and/or OGTTt = 120 levels. P-values for the difference between diabetic and control subjects in subjects with vs. subjects without a history of anti-hypertensive medication are 0.02 for glyoxylate and 0.77 for glucose.
Figure 4.
Metabolite levels differ in diabetic subjects having a history an intake of anti-hypertensive medication.
Subjects with anti-hypertension medication (med) are dark red or blue; subjects with no history of anti-hypertensive medication (no med) are light red or blue. OGTTt = 120 samples were analyzed with the SIM method. The study participants were categorized as type-2 diabetic (n = 47) or control (n = 51) based on FPG and/or OGTTt = 120 levels. Levels of glyoxylate, fructosamine and dihomo-gamma linolenic acid are depicted. Furthermore, OGTTt = 0 samples were analyzed by MxP™ Eicosanoid analysis. The study participants here were categorized as type-2 diabetic (n = 58) or control (n = 177) based on FPG and/or OGTTt = 120 levels. Levels of the eicosanoids metabolites thromboxane B2, prostaglandin E2, and 15-hydroxyeicosatetranoic are depicted. When comparing diabetic and control subjects with and without a history of anti-hypertensive medication, metabolite levels differ: hexosamines are more strongly increased in diabetic subjects with a history of anti-hypertensive medication, while eicosanoid and eicosanoid precursor levels are regulated in different directions in diabetic patients with or without a history of anti-hypertensive medication compared to their corresponding non-diabetic controls. P-values for the difference between diabetic and healthy subjects in subjects with vs. subjects without a history of anti-hypertensive medication are 0.02 for glyoxylate, 0.01 for dihomo-gamma linolenic acid, 0.04 for fructosamine, 0.02 for 5-Hydroxyeicosatetraenoic 15-Hydroxyeicosatetraenoic acid, 0.01 for thromboxane B2 and 4.58E-04 for prostaglandine E2.
Figure 5.
Metabolic alterations point to changes in Cox/Lox enzyme activity and the RhoA kinase pathway.
The diagram depicts pathways and processes providing a putative molecular basis for the association of diabetes with hypertension. Type-2 diabetic patients with a history of taking anti-hypertensive medication and normotensive diabetic patients were compared to their respective non-diabetic controls. Arrows in dark red indicate an increase or decrease of the specific metabolites in type-2 diabetic patients taking anti-hypertensive medication compared to controls; arrows in light red indicate an increase or decrease of the specific metabolites in type-2 diabetic patients not taking anti-hypertensive medication compared to controls. Arrows in grey indicate an increase or decrease of depicted metabolites as described in the literature. Type-2 diabetic patients taking hypertensive medication exhibit a stronger elevation of hexosamines and glyoxylate upon glucose challenge in comparison to normotensive diabetics. Concomitantly, we observed an increase of arachidonic and dihomo-gamma linolenic acids in type-2 diabetic patients taking anti-hypertensive medication and a decrease in normotensive diabetic patients compared to the corresponding non-diabetic controls. In addition, the ratios of some metabolites derived from arachidonic acid by cyclooxygenase and lipoxygenase activities differ between diabetic and control subjects. Observed metabolic changes may further support an involvement of the RhoA pathway in the development of diabetes. An increase of glyoxylate might indicate a decrease in AGT2 activity which also leads to increased levels of asymmetric dimethylarginine, decreased NO availability and corresponding increased activity of the RhoA kinase pathway. Similarly, hexosamines can also affect RhoA kinase pathway activity.