Long-term incidence of microvascular disease after bariatric surgery or usual care in patients with obesity, stratified by baseline glycaemic status: a post-hoc analysis of participants from the Swedish Obese Subjects study

Abstract

Summary Background Bariatric surgery in patients with obesity and type 2 diabetes is associated with diabetes remission and prevention of complications. The long-term effects of bariatric surgery on microvascular complications in patients with prediabetes are unknown. Methods The prospective, matched Swedish Obese Subjects study examines outcomes after bariatric surgery. Patients were recruited between September 1, 1987, and January 31, 2001. Age was 37–60 years and BMI was ≥34 kg/m2 in men and ≥38 kg/m2 in women. The surgery group (n=2010) underwent gastric bypass (13·2%), banding (18·7%), or vertical banded gastroplasty (68·1%), and controls (n=2037) received usual care. After exclusion of 4 patients with suspected type 1 diabetes, and 11 patients with unknown glucose status at baseline, 4032 of the 4047 participants in the SOS study were included in the current analysis. The main outcome of this report was incidence of microvascular events (retinopathy, diabetic kidney disease, and neuropathy, whichever came first), obtained from nationwide registers, in subgroups stratified by baseline glucose status (euglycemia n=2838; prediabetes n=591; screen-detected diabetes n=246; established diabetes n=357). Data were analyzed both by intention to treat and per protocol. Median follow-up was 19 years. This study is registered with ClinicalTrials.gov, NCT01479452. Findings There were 374 first-time microvascular events in the control group and 224 in the surgery group (hazard ratio, 0·56; 95% CI 0·48–0·66; p<0·0001). There was a significant interaction between baseline glucose status and treatment effect (p=0.0003), and unadjusted hazard ratios for comparing the surgery group to the control group were lowest in the subgroup with prediabetes (0·18; 95% CI 0·11–0·30), followed by subgroups with screen-detected diabetes (0·39; 95% CI 0·24–0·65), established diabetes (0·54; 95% CI 0·40–0·72), and euglycemia (0·63; 95% CI 0·48–0·81). In patients with baseline prediabetes, treatment was associated with reduced incidence of microvascular events both in those who developed diabetes and in those who remained diabetes free during follow-up. Interpretation Bariatric surgery was associated with reduced risk of microvascular complications in all subgroups, but the greatest relative risk reduction was observed in patients with baseline prediabetes. Our results indicate that prediabetes should be treated aggressively to prevent future microvascular events.

The Role of Bariatric Surgery in the Treatment of Type 2 Diabetes in Morbidly Obese Patients

“…According a recent study, having bariatric surgery being done in addition to intensive medical therapy for the treatment of type 2 diabetes in patients with BMI 27-43, yielded significant results in the reduction and sometimes resolving of diabetes compared to intensive medical therapy alone [12]. Another recent study showed that the risk of microvascular complications is reduced due to improved glycemic control in pre diabetic patients who undergo bariatric surgery [13].…”

Comorbidities as an Indication for Metabolic Surgery

“…Furthermore, the ideal time point for considering metabolic surgery needs to be defined and likely also depends on the comorbidities present. T2DM is a good example: patients with long-term T2DM and a need for insulin therapy have a much lesser likelihood for diabetes remission than patients with an impaired glucose tolerance [2,18,19]. Based on the EOSS, a patient with insulin therapy and a high insulin dose would be graded as EOSS 2 or 3, depending on the severity of the diabetic complications.…”

“…Hence, one could argue that even patients with T2DM and EOSS 1 should be considered for metabolic surgery since they would be likely to receive the strongest benefit. The importance of operating earlier rather than later is further supported by the findings of the SOS study, which shows that metabolic surgery has a lower impact on the reduction of macro- and microvascular events the longer the T2DM existed prior to surgery [2,18]. In contrast, a recent meta-analysis did not find a relationship between the duration of T2DM and the efficacy of metabolic operations regarding the reduced incidence or improvement of microvascular complications [8].…”

“…Regarding the time point of surgery, a recent study investigating the benefits of surgery at different stages of diabetes progression showed that patients with pre-diabetes who had surgery received the clearest benefit regarding the development of microvascular complications [18]. These findings led to the newest German S3 guideline from the German Association of General and Visceral Surgery, which were also approved by the German Diabetes Association, for ‘surgery of obesity and metabolic diseases' which grant a much bigger role for metabolic surgery in the treatment of T2DM in obese patients [14].…”

Does addressing prediabetes help to improve population health?

“…2,4,5 NHANES is a programme of population-based studies designed to assess the health of adults and children in the United States. For the current analysis, Ali and colleagues used NHANES data from 1988-1994, 1999-2004, 2005-2010 and 2011-2014 Some of the findings from the analysis conducted by Ali and colleagues also imply that any additional cardiovascular benefits from targeting specifically pre-diabetic individuals would be modest.…”