Effect of an alpha-glucosidase inhibitor on glomerular basement membrane anionic sites in streptozotocin induced mildly diabetic rats

Effects of glucose-lowering agents on surrogate endpoints and hard clinical renal outcomes in patients with type 2 diabetes

Diabetic kidney disease (DKD) represents an enormous burden in patients with type 2 diabetes mellitus (T2DM). Preclinical studies using most glucose-lowering agents have suggested renal-protective effects, but the proposed mechanisms of renoprotection have yet to be defined, and the promising results from experimental studies remain to be translated into human clinical findings to improve the prognosis of patients at risk of DKD. Also, it is important to distinguish effects on surrogate endpoints, such as decreases in albuminuria and estimated glomerular filtration rate (eGFR), and hard clinical endpoints, such as progression to end-stage renal disease (ESRD) and death from renal causes. Data regarding insulin therapy are surprisingly scarce, and it is nearly impossible to separate the effects of better glucose control from those of insulin per se, whereas favourable preclinical data with metformin, thiazolidinediones and dipeptidyl peptidase (DPP)-4 inhibitors are plentiful, and positive effects have been observed in clinical studies, at least for surrogate endpoints. The most favourable renal results have been reported with glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter type-2 inhibitors (SGLT2is). Significant reductions in both albuminuria and eGFR decline have been reported with these classes of glucose-lowering medications compared with placebo and other glucose-lowering agents. Moreover, in large prospective cardiovascular outcome trials using composite renal outcomes as secondary endpoints, both GLP-1RAs and SGLT2is added to standard care reduced renal outcomes combining persistent macro-albuminuria, doubling of serum creatinine, progression to ESRD and kidney-related death; however, to date, only SGLT2is have been clearly shown to reduce such hard clinical outcomes. Yet, as the renoprotective effects of SGLT2is and GLP-1RAs appear to be independent of glucose-lowering activity, the underlying mechanisms are still a matter of debate. For this reason, further studies with renal outcomes as primary endpoints are now awaited in T2DM patients at high risk of DKD, including trials evaluating the potential add-on benefits of combined GLP-1RA-SGLT2i therapies.

Acarbose: safe and effective for lowering postprandial hyperglycaemia and improving cardiovascular outcomes

α-Glucosidase inhibitors (AGIs) are a class of oral glucose-lowering drugs used exclusively for treatment or prevention of type 2 diabetes mellitus. AGIs act by altering the intestinal absorption of carbohydrates through inhibition of their conversion into simple sugars (monosaccharides) and thus decrease the bioavailability of carbohydrates in the body, significantly lowering blood glucose levels. The three AGIs used in clinical practice are acarbose, voglibose and miglitol. This review will focus on the cardiovascular properties of acarbose. The current available data suggest that AGIs (particularly acarbose) may be safe and effective for the treatment of prediabetes and diabetes.

Inhibition ofα‐Glucosidase by Aqueous Extracts of Some Potent Antidiabetic Medicinal Herbs

Diabetes mellitus is one of the most prevalant diseases of adults. Agents with alpha-glucosidase inhibitory activity have been useful as oral hypoglycemic drugs for the control of hyperglycemia in patients with type 2; noninsulin-dependent, diabetes mellitus (NIDDM). Investigation of some medicinal herbs: Urtica dioica, Taraxacum officinale, Viscum album, and Myrtus communis with alpha-glucosidase inhibitor activity was conducted to identify a prophylactic effect for diabetes in vitro. All plants showed differing potent alpha-glucosidase inhibitory activity. However, Myrtus communis strongly inhibited the enzyme (IC50 = 38 microg/mL). The inhibitory effect of these plants and some common antidiabetic drugs against the enzyme source (baker's yeast, rabbit liver, and small intestine) were also searched. Approximately all inhibitors used in this study showed quite different inhibitory activities, according to alpha-glucosidase origins. Furthermore, subsequent separation of the active material from Myrtus communis by HPLC showed that only one fraction acted as an a-glucosidase inhibitor.

Acarbose treatment lowers generation and serum concentrations of the protein-bound solute p-cresol: a pilot study

Several protein-bound uremic retention solutes (including p-cresol) originate from colonic bacterial fermentation of protein. Higher colonic availability of carbohydrates drives this process towards lower production of toxic metabolites. Small intestinal alpha-glucosidase inhibitors like Acarbose (Glucobay) enhance the amount of undigested carbohydrates reaching the colon. We studied the effect of Acarbose on generation and serum concentrations of p-cresol. Nine healthy volunteers (age 25 (22-36) years) with a creatinine clearance of 89.6 ml/min/1.73 m(2) (85.5-116.4) were treated with Acarbose for 3 weeks. Dose was gradually increased to reach 300 mg/day after 1 week. Blood sampling, 24-h urine and stool collections on 3 consecutive days were performed before and during the last days of the treatment period. p-Cresol generation was estimated from mean 24-h urinary elimination. Gastrointestinal side effects, if present, were mild to moderate. Serum concentrations of p-cresol declined significantly after Acarbose treatment (before: 1.14 mg/l (0.93-3.03); after: 1.11 mg/l (0.31-1.82); P=0.047). Urinary excretion of p-cresol, reflecting its colonic generation rate, was significantly lower after treatment (before: 29.93 mg/day (6.79-75.19); after: 10.54 mg/day (1.08-30.85); P=0.031). The fecal excretion of nitrogen increased after treatment (before: 1.04 g/day (0.47-2.29); after: 1.99 g/day (0.76-3.08); P=0.047). This pilot study suggests that Acarbose treatment lowers generation and serum concentrations of the protein-bound uremic solute p-cresol. Although further confirmation is warranted, the data may point to a novel treatment option for chronic kidney disease patients in view of the potential toxic effects of p-cresol and related substances.