In a cohort of obese patients, bariatric surgery reduced long-term risk for microvascular complications in all subgroups, with the greatest reduction seen among those with prediabetes.

For the Swedish Obese Subjects study, which was published in Lancet: Diabetes & Endocrinology, researchers enrolled 4047 patients (aged 37-60 years) between September 1, 1987, and January 31, 2001. Male patients had a body mass index (BMI) of ≥34 kg/m2, and female patients had a body mass index of ≥38 kg/m2.

Among the surgery group (n=2010), 13% underwent gastric bypass, 19% underwent gastric banding, and 68% received vertical-banded gastroplasty. Control group patients (n=2037) received usual care.

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The researchers assessed body weight and obtained completed questionnaires at baseline, 6 months, and years 1, 2, 3, 4, 6, 8, 10, 15, and 20, and measured biochemical variables at baseline and years 2, 10, and 15.

Patients were divided into subgroups based on established diabetes and baseline glycemic status, with normal defined as a fasting blood glucose concentration <5 mmol/L, prediabetes defined as 5 to 6 mmol/L, and screen-detected diabetes defined as ≥6.1 mmol/L at baseline visit without previous diagnosis.

The researchers excluded 4 patients with suspected type 1 diabetes and 11 patients with unknown glycemic status at baseline, resulting in a final study population of 4032 patients. Overall, 2838 patients had normal blood glucose, 591 had prediabetes, 357 had established diabetes, and 246 had screen-detected diabetes.

During follow-up (median, 19 years), 374 incident cases of microvascular disease occurred in the control group compared with 224 in the surgery group (hazard ratio [HR], 0.56; 95% CI, 0.48-0.66; P <.0001). The researchers reported a significant interaction between baseline glycemic status and treatment effect on microvascular disease incidence (P =.0003).

In an unadjusted analysis, the subgroup with the lowest HR for microvascular complications was prediabetes (HR, 0.18; 95% CI, 0.11-0.30), followed by screen-detected diabetes (HR, 0.39; 95% CI, 0.24-0.65), established diabetes (HR, 0.54; 95% CI, 0.40-0.72), and normoglycemia (HR, 0.63; 95% CI, 0.48-0.81).

For patients with prediabetes, surgery yielded a decreased incidence of microvascular events, regardless of whether they were diagnosed with diabetes during follow-up.

These results, the researchers wrote, show “that exposure to glucose concentrations that seem harmless in cross-sectional studies can cause significant damage if they persist over a long time. Our data suggest that prediabetes should be treated aggressively, rather than waiting until glucose concentrations reach the diagnostic range for diabetes.”

The researchers added that the development of effective, nonsurgical treatments with the aim of tackling prediabetes are needed.

Disclosures: The researchers report several financial disclosures with pharmaceutical companies.