Diabetes remission as a concept became a focus of interest as a result of outcomes with bariatric surgery. Since this is a chronic condition, and long-term data are lacking, “cure” as a term is seldom used. Normalization of blood glucose and HgA1c in the absence of antiglycemic medications defines remission. This has been historically a rare occurrence with medical therapy, but bariatric surgery has led to the International Diabetes Federation suggesting surgical therapy as a valid option for the treatment of diabetes.

A recent meta-analysis of 19 different studies revealed that bariatric surgery overall is associated with a 0.33 risk reduction for the presence of type 2 diabetes postoperatively [8]. As multiple single-institution studies have previously shown (Table 28.2), this meta-analysis again underlines a significant difference in risk reduction between RYGB/biliopancreatic diversion (BPD) and AGB (0.26 vs 0.44, p < 0.0001). A few recent randomized controlled trials have assessed the effect of bariatric surgery on diabetes control and have provided high quality data in this topic. The first one evaluated 150 obese (BMI > 27) patients with poorly controlled diabetes [9]. Patients were randomized to intense medical therapy, consisting of lifestyle counseling, weight management programs, incretin analogs, and frequent visits with an endocrinologist, vs bariatric surgery, and the purpose of the study was to achieve diabetes control. Diabetes control (12 % vs 42 % vs 37 %) and remission (0 vs 42 % vs 27 %) at 12-months after surgery were significantly more common in the bariatric surgery groups than medical treatment. A similar study from Italy on 60 severely obese patients with poorly controlled diabetes, randomized patients to intense medical therapy vs RYGB vs BPD [10]. Diabetic remission at 48 months after surgery was significantly higher after RYGB (75 %) and BPD (95 %) compared to medical treatment (nil). The intensity of medical therapy is illustrated on the fact that it led to an 8 % decrease in BMI and discontinuation of antihypertensive medications in 70 % of the group.

The effect of bariatric surgery on diabetes is not only about remission, but also about preventing its development in the severely obese. In the SOS study, the adjusted odds ratio for new-onset diabetes was 0.25 in the surgery group compared to the medically treated group [18]. The prevalence at 10 years after surgery was 5–10 %. In comparison, the Framingham Study addressed the question of the effect of medical weight loss on diabetes prevention [19]. Overweight patients (total 618) who lost at least 1 lb/year were compared to patients with weight regain and ones with weight stable in this time period. Adjusting for years of follow-up, diabetes at the weight-stable patients occurred in 8.1 per 1,000 person-years; sustained weight loss led to a 37 % lower risk of diabetes development (relative risk 0.63). Similarly, the Diabetes Prevention Program study randomized over 3,000 overweight and obese (mean BMI of 34) patients with pre-diabetes to intense lifestyle changes vs metformin vs placebo [20]. The incidence of diabetes in this high-risk group at 10 years was 40 %. Lifestyle modification (including low-caloric low-fat diet, moderate physical activity, and one-to-one educational sessions) was associated with a significant decrease in the prevalence of diabetes (OR 0.42), but less to what is achieved with bariatric surgery.

The effect of bariatric surgery on hypertension is variable, but all studies universally demonstrate improvement after surgery. In a comparison analysis of 418 patients undergoing RYGB, hypertension remission was reported in 53 % of the 169 hypertensive patients at 2 years after bariatric surgery, and 42 % at 6 years [6]. Using meta-analytic methods on almost 7,000 bariatric patients, hypertension resolved postoperatively in 65.6 % and improved in 81.8 % [5]. There was a significant difference between the stapling procedures (RYGB and DS) and AGB, with almost a twofold difference in the rate of hypertension remission after intervention. A more recent analysis reported similar findings with 0.52 risk reduction for hypertension after bariatric surgery [8]. Similarly, another meta-analysis with a total of 243 randomized bariatric patients and almost 17,000 observed nonrandomized patients found hypertension improvement or resolution in 75 and 74 %, respectively [21].

Prospective long-term data on remission of hypertension show a less pronounced impact compared to diabetes. In the 3-year follow-up of the LABS study, 38.2 and 17.4 % of the patients who underwent RYGB and AGB, respectively, had remission of hypertension [4]. The SOS study showed that at 2 years after bariatric surgery (mostly VBG), hypertension resolution occurred in 34 % of the patients, while this number dropped to 19 % at 10 years. Given the established relationship between advancing age and the prevalence of hypertension, this drop in hypertension resolution at 10 years after intervention should not be viewed as failure of bariatric surgery to control this comorbidity, but rather as an evolution of the nature process of aging.

Abnormalities in lipids, lipoproteins, and triglycerides are common. They are a substantial contributor to the metabolic syndrome and represent a major risk factor for cardiovascular disease in diabetic and nondiabetic patients. Metabolic surgery allows for improvement in the lipid profiles in the majority of patients. In a large meta-analysis from 2004, improvements in hypertriglyceridemia, hypercholesterolemia, and hyperlipidemia occurred in 92.8 % (912 of 983), 86.6 % (1,777 of 2,051), and 83 % (846 of 1,019), respectively [5]. These numbers for RYGB and DS exceeded 90 % for all measures. A more recent meta-analysis evaluating overall cardiovascular risk reduction after surgery, reported a hyperlipidemia risk reduction of 0.39 for patients undergoing bariatric surgery; RYGB and BPD were associated with a risk reduction of 0.26 [8]. A second recent review of 25 bariatric studies reporting on lipid outcomes found resolution or improvement of dyslipidemia in 76 % of patients participating in a bariatric surgery randomized control trial and 68 % of patients included in observational studies [21].

Long-term assessment of lipid profiles after RYGB demonstrates sustained improvement in dyslipidemia with surgery [6]. Normalization for HDL, LDL, and triglycerides 6 years after RYGB was seen in 67, 53, and 71 % of patients, respectively. Again, there were minimal differences in these rates from year 2 to year 6 after RYGB. Recent data from the LABS study shows that at 3 years from RYGB, the majority of patients normalize their LDL (59.7 %), HDL (85.6 %), and triglycerides (85.8 %). Improvements to a lesser degree were also seen after AGB (22.7, 67.3, and 62.1 %, respectively) [4]. Long-term data are also available from the SOS study [11]. Normalization of LDL, HDL, and triglycerides 10 years after bariatric surgery were found in 21, 73, and 46 % of patients, respectively. Interestingly, there were no significant differences in the rates of resolution for HDL and LDL abnormalities between year 2 and year 10 after surgical intervention, suggesting that the benefit with bariatric surgery is seen early and is long lasting.