Dennis K. Yue

Efficacy and safety of canagliflozin in subjects with type 2 diabetes and chronic kidney disease

Canagliflozin is a sodium glucose co‐transporter 2 inhibitor in development for treatment of type 2 diabetes mellitus (T2DM). This study evaluated the efficacy and safety of canagliflozin in subjects with T2DM and stage 3 chronic kidney disease [CKD; estimated glomerular filtration rate (eGFR) ≥30 and <50 ml/min/1.73 m2].

Changes in Hepatic Glutathione Metabolism in Diabetes

Glutathione is important in the regulation of the redox state, and a decline in its tissue level has often been considered to be indicative of increased oxidative stress in diabetes. In this study of diabetic rats, the level of hepatic glutathione was normal unless food intake was restricted. Thus, the previous report of a reduction in hepatic glutathione in diabetes is likely to be the result of food deprivation rather than diabetes alone. In contrast to changes characteristic of oxidative stress, the efflux of glutathione in bile from diabetic animals was significantly decreased, whereas hepatic mixed disulfides were unchanged, and the hepatic γ-glutamyltransferase activity was considerably increased. These changes were not reproduced by food deprivation. The decrease in biliary excretion of glutathione in diabetes may reflect an attempt to conserve glutathione by activation of the hepatic γ-glutamyl cycle. We conclude that the disturbances of glutathione metabolism in diabetes are not typical of those seen in oxidative stress or food restriction.

High glucose alters matrix metalloproteinase expression in two key vascular cells: potential impact on atherosclerosis in diabetes

Diabetes is a major risk factor for atherosclerosis. Hyperglycemia is an underlying contributing factor; however, the mechanisms that mediate the vascular complications are not yet fully understood. In the present study, we provide evidence that elevated glucose induces discordant matrix metalloproteinase (MMP) expression from two key vascular cells, endothelial cells and macrophages. Our results clearly indicate that high glucose (25 mM) induced endothelial cell expression and activity of the collagenase, MMP-1 and the gelatinase, MMP-2, whilst reducing expression of the stromelysin, MMP-3 (P<0.05). Similarly, our results show that high glucose (25 mM) induces expression and activity of MMP-9 from monocyte-derived macrophages (P<0.05). High glucose culture did not affect metalloproteinase inhibitor (TIMP-1) expression. Our results suggest for the first time that high glucose exposure induced discordant regulation of the MMP/TIMP system in vascular cells. The increased MMP-1, MMP-2 and MMP-9 activities induced by high glucose exposure could promote matrix degradation thereby accelerating atherogenesis and potentially reducing plaque stability in diabetes.

Increased Matrix Metalloproteinase-9 Predicts Poor Wound Healing in Diabetic Foot Ulcers

OBJECTIVE—We studied the relationships of diabetic ulcer wound fluid matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), and transforming growth factor-ß1 (TGF-ß1) with wound healing rate. RESEARCH DESIGN AND METHODS—The ulcers were cleansed to remove exudates, and wound fluids were collected for analysis of MMP-2 and -9, TIMP-1, and TGF-ß1. RESULTS—At presentation, MMP-9 and the MMP-9–to–TIMP-1 ratio correlated inversely with the wound healing rate at 28 days (P < 0.001). MMP-9 and the MMP-9–to–TIMP-1 ratio were lower in the 23 patients who achieved complete healing at 12 weeks versus the 39 who did not. The pro–MMP-9 concentration was predictive of healing within 12 weeks. Addition of cutoffs for TIMP-1 (>480 pg/ml) and TGF-ß (>115 pg/ml) further improved its predictive power (area under the curve 0.94). CONCLUSIONS—These findings suggest that a milieu with high MMP-9 may be indicative of inflammation and poor wound healing. Measurements of MMP-9, TIMP-1, and TGF-ß in wound fluid may help to identify ulcers at risk of poor healing.

TBI or not TBI: that is the question. Is it better to measure toe pressure than ankle pressure in diabetic patients?

Aims Measurement of ankle blood pressure is a simple method of assessing lower limb arterial blood supply. However, its use in diabetes has been questioned due to the presence of medial artery calcification. Measurement of toe blood pressure has been advocated as an alternative but it is technically more difficult. The aim of this study was to obtain information to guide clinicians as to when pressure measurements should be taken at the toe.

Long-Term Complications and Mortality in Young-Onset Diabetes: Type 2 diabetes is more hazardous and lethal than type 1 diabetes

OBJECTIVE To evaluate long-term clinical outcomes and survival in young-onset type 2 diabetes (T2DM) compared with type 1 diabetes (T1DM) with a similar age of onset. RESEARCH DESIGN AND METHODS Records from the Royal Prince Alfred Hospital Diabetes Clinical Database, established in 1986, were matched with the Australian National Death Index to establish mortality outcomes for all subjects until June 2011. Clinical and mortality outcomes in 354 patients with T2DM, age of onset between 15 and 30 years (T2DM15–30), were compared with T1DM in several ways but primarily with 470 patients with T1DM with a similar age of onset (T1DM15–30) to minimize the confounding effect of age on outcome. RESULTS For a median observation period of 21.4 (interquartile range 14–30.7) and 23.4 (15.7–32.4) years for the T2DM and T1DM cohorts, respectively, 71 of 824 patients (8.6%) died. A significant mortality excess was noted in T2DM15–30 (11 vs. 6.8%, P = 0.03), with an increased hazard for death (hazard ratio 2.0 [95% CI 1.2–3.2], P = 0.003). Death for T2DM15–30 occurred after a significantly shorter disease duration (26.9 [18.1–36.0] vs. 36.5 [24.4–45.4] years, P = 0.01) and at a relatively young age. There were more cardiovascular deaths in T2DM15–30 (50 vs. 30%, P < 0.05). Despite equivalent glycemic control and shorter disease duration, the prevalence of albuminuria and less favorable cardiovascular risk factors were greater in the T2DM15–30 cohort, even soon after diabetes onset. Neuropathy scores and macrovascular complications were also increased in T2DM15–30 (P < 0.0001). CONCLUSIONS Young-onset T2DM is the more lethal phenotype of diabetes and is associated with a greater mortality, more diabetes complications, and unfavorable cardiovascular disease risk factors when compared with T1DM.

The Effect of Aldose Reductase Inhibition on Motor Nerve Conduction Velocity in Diabetic Rats

This study examined the effects of an aldose reductase inhibitor (CP 45634, Sorbinil, Pfizer, New York, New York) on the neuropathy of streptozotocin-induced diabetic rats. Sorbinil treatment for 4 wk reduced sciatic nerve sorbitol concentration and improved motor nerve conduction velocity in diabetes of 2–9 mo duration. It remains to be determined whether Sorbinil can prevent chronic diabetic neuropathy.

Efficacy and safety of canagliflozin over 52 weeks in patients with type 2 diabetes mellitus and chronic kidney disease

This study evaluated the efficacy and safety of canagliflozin, a sodium glucose co‐transporter 2 inhibitor, in patients with type 2 diabetes mellitus (T2DM) and within a subset of Stage 3 chronic kidney disease (CKD; estimated glomerular filtration rate [eGFR] ≥30 and <50 ml/min/1.73 m2).

Decreased matrix degradation in diabetic nephropathy: effects of ACE inhibition on the expression and activities of matrix metalloproteinases.

Aims/hypothesisExtracellular matrix accumulation is thought to be involved in the pathogenesis of diabetic nephropathy. Increased matrix synthesis has been well documented but the effects of diabetes on degradative pathways, particularly in the in vivo setting, have not been fully explored. Furthermore, the effect of renoprotective therapies on matrix accumulation through these pathways has not been examined. We investigated the degradative pathway of type IV collagen and the effects of ACE inhibition in experimental diabetic nephropathy. MethodsDiabetes was induced in 16 rats by administrating streptozocin; 8 of the diabetic rats were allocated at random to receive the ACE inhibitor perindopril (2 mg/l) in their drinking water and 8 age and weight matched rats served as controls. Gene expression of matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) was measured by RT-PCR and type IV collagen content by immunohistochemistry. MMP activities were determined by degradation of a radiolabelled substrate and by zymography. ResultsSix months of diabetes was associated with a decrease in mRNA and enzymatic activity of MMP-9 (21 % and 51 % respectively, p < 0.05 vs control) and a 51 % increase in TIMP-1 mRNA (p < 0.05 vs control). By contrast, MMP-2 mRNA was increased but its activity decreased (43 % and 43 % respectively, p < 0.05 vs control). Total degradative capacity of kidney tissue from diabetic rats was also lower (Control: 48 ± 7 %, Diabetic: 33 ± 6 %, p < 0.05). Activation of latent MMPs with amino-phenylmercuric acetate increased matrix degradation by two-fold. However the relative decrease associated with experimental diabetes still remained. All diabetes-associated changes in MMP and TIMP mRNA and activities were attenuated by perindopril treatment in association with reduced type IV collagen accumulation. Conclusions/interpretationThese results indicate that the impairment of matrix degradation contributes to matrix accumulation in diabetic nephropathy and that the beneficial effects of ACE inhibition could in part be mediated by modulation of changes in matrix degradative pathways. [Diabetologia (2002) 45: 268–275]

Augmentation of central arterial pressure in Type 2 diabetes

Aims  Aortic systolic blood pressure has been shown to be augmented in Type 1 diabetes, indicative of more rapid pulse wave reflection due to increased arterial stiffness. This abnormality is more pronounced in diabetic males. The aim of this study was to examine the effects of diabetes on augmentation of aortic systolic pressure in subjects with Type 2 diabetes.