Conference Coverage

Diuretics linked to diabetic amputations in T2DM



Diuretics may need to be used cautiously in patients with type 2 diabetes mellitus who are at risk of lower limb amputation, suggest observational study findings presented at the annual meeting of the European Association for the Study of Diabetes.

Dr. Ronan Roussel of Hôpital Bichat, Assistance Publique Hôpitaux de Paris (France) Sara Freeman/MDedge News

Dr. Ronan Roussel

A significant and independent increase in the risk of lower limb events, predominantly lower-extremity amputations was seen among patients with type 2 diabetes mellitus (T2DM) who were treated with diuretics versus those who were not. The adjusted hazard ratios in a propensity-matched cohort was 1.60 (95% confidence interval, 1.06-2.42; P = .027) for lower limb events, 2.13 (95% CI, 1.17-3.87; P = .013) for lower limb amputations, and 1.12 (95% CI, 0.70-1.79; P = .6443) for lower limb revascularizations.

“We know diabetes is a leading cause of nontraumatic lower limb amputations in the world,” and thus a very important public health issue, said study investigator Ronan Roussel, MD, PhD, of Hôpital Bichat, Assistance Publique Hôpitaux de Paris. “Many contributing factors are identified, susceptibility to infection, impaired wound healing, peripheral neuropathy; but the most important is the presence of peripheral arterial disease.”

The risk of diabetic amputations is of specific interest because of the recent findings from CANVAS, where treatment with canagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, was linked to an almost doubled rate of amputations versus placebo (HR, 1.97; 95% CI, 1.41-2.75) in patients with T2DM.

Conflicting results have been seen in observational studies with other SGLT2 inhibitors, however, and it’s not clear if the risk of amputations is just seen with canagliflozin or if it may be a class effect. The underlying mechanism is unknown, but one theory is that hypovolemia may be involved. If this is the case, Dr. Roussel explained, then diuretics would have a similar safety profile as SGLT2 inhibitors in terms of increasing the risk of amputations.

The aim of the present study was to look at the association between lower limb events and diuretic usage in patients with T2DM. Data on 1,459 subjects with T2DM treated with diuretics and data on lower limb events and amputations were obtained from the single-center SURDIAGENE study. Of these, 670 were and 789 were not taking diuretics.

Baseline differences between diuretic and nondiuretic users were seen, such as diuretic users being older (67 vs. 63 years), having longer diabetes duration (16 vs. 13 years), and being more likely to have cardiovascular disease (32.5% vs. 23.4%). A propensity-score approach was used to even out these differences, leaving a population of 1,074 subjects in the final matched cohort.

Over a median follow-up of 7.2 years, 12.7% of diuretic and 7.2% of nondiuretic users experienced lower limb events (P = .001). In multivariate and sensitivity analyses, lower limb amputations remained significantly higher in patients who had been treated with a diuretic than in those who had not.

These are “hypothesis-generating” data, Dr. Roussel pointed out and “we don’t want to be overconclusive, of course.” However, they may explain the risk signal seen with SGLT2 inhibitors in the CANVAS study. Further studies are needed to explore the role of drug-induced hypovolemia in the association between the use of diuretics and lower limb events.

Dr. Vas Prashanth Sara Freeman/MDedge News

Dr. Vas Prashanth

EASD delegate Prashanth Vas, MBBS, MRCP, PhD, noted during the discussion that the use of diuretics was ubiquitous. “Nearly everyone uses diuretics,” he said. The potential risk of lower limb amputation and treatment with SGLT2 inhibitors had “been vexing us for some time since the data from CANVAS came out.”

Dr. Vas, who is a consultant diabetologist and diabetic foot specialist at King’s College Hospital NHS Foundation in London, went on to ask why only canagliflozin was found to be associated with amputations and not the other SGLT2 drugs.

Dr. Roussel responded that data were still needed on the other drugs in this class and that they needed to be treated with caution. The literature is not so clear, he admitted.

“It’s important that you noted it’s a single-center study,” Dr. Vas countered. “It’s very important to have multicenter data. An amputation is a decision made by someone. An amputation in one center may not be an amputation in another center.”

The SURDIAGENE study was supported by grants from the French Ministry of Health, the Association Française des Diabétiques, and the Groupement pour l’Etude des Maladies Métaboliques et Systémiques. Dr. Roussel reported relationships with Janssen, Merck, Sanofi-Aventis, AstraZeneca, and Boehringer Ingelheim. Dr. Vas was not involved in the study or analysis.

SOURCE: Roussel R et al. EASD 2018, Abstract 12.

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