Sulfonylurea-induced decrease of muscle capillary basement membrane thickness in diabetes

Cardiovascular safety of sulfonylureas: a meta-analysis of randomized clinical trials

AIM

Cardiovascular safety of sulfonylurea has been questioned by some authors. This article aims at collecting all available data on this issue from randomized trials.

METHODS

A meta-analysis was performed including all trials with a duration of at least 6 months, comparing a sulfonylurea with a non-sulfonylurea agent in type 2 diabetes. Major cardiovascular events (MACE) and mortality were retrieved and combined to calculate Mantel-Haenzel odds ratio (MH-OR).

RESULTS

Of the 115 selected trials, 62 reported information on MACE, and 30 reported at least one event. MH-OR for sulfonylurea was 1.08 [0.86-1.36], p = 0.52 (1.85 [1.20-2.87], p = 0.005, in the five trials vs. DPP4 inhibitors, no significant differences vs. other comparators). The MH-OR for myocardial infarction and stroke was 0.88 [0.75-1.04], p = 0.13 and 1.28 [1.03-1.60], p = 0.026, respectively. Mortality was significantly increased with sulfonylureas (MH-OR: 1.22 [1.01-1.49], p = 0.047).

CONCLUSIONS

In type 2 diabetes, the use of sulfonylureas is associated with increased mortality and a higher risk of stroke, whereas the overall incidence of MACE appears to be unaffected. Significant differences in cardiovascular risk could be present in direct comparisons with specific classes of glucose-lowering agents, such as DPP4 inhibitors, but this hypothesis needs to be confirmed in long-term cardiovascular outcomes trials. The results of this meta-analysis need to be interpreted with caution, mainly because of limitations in trial quality and under-reporting of information on cardiovascular events and mortality. However, the cardiovascular safety of sulfonylureas cannot be considered established unless it is evaluated in long-term cardiovascular outcomes trials.

Arrest of glomerulopathy in diabetic dogs by improved glycaemic control

In order to assess the extent to which the progression of diabetic glomerulopathy can be arrested or reversed by improved glycaemic control, glomerular structure has been assessed in dogs randomly divided between a non-diabetic group and three alloxan diabetic groups: dogs assigned to poor glycaemic control for five years (PC), dogs assigned to good glycaemic control for five years (GC), and dogs assigned to poor glycaemic control for 2.5 years followed by good glycaemic control for 2.5 years (P----GC). Glomerular volume, the fractional volume of mesangium as estimated by light microscopy and thickness of glomerular basement membrane as estimated by electron microscopy were significantly greater than normal at 2.5 years of poor glycaemic control, and were even greater at five years. Kidney weight and the frequency of glomerular obliteration were significantly greater than normal at five years of poor control. The development of these renal abnormalities was significantly inhibited if good glycaemic control was begun within the first weeks of diabetes. Good control following 2.5 years of poor control (group P----GC) arrested the progression of the renal abnormalities, but no reversal of the lesions toward normal was apparent.