Changes in bone quality after Roux-en-Y gastric bypass: A prospective cohort study in subjects with and without type 2 diabetes

BACKGROUND

Obesity and type 2 diabetes (T2D) are associated with an increased risk of skeletal fractures despite a normal areal bone mineral density (aBMD) and low bone turnover, possibly due to reduced bone material strength. Roux-en-Y gastric bypass (RYGB) enables a substantial and persistent weight loss and resolution of obesity related comorbidities such as T2D. However, the procedure induces a decrease in aBMD and increased bone turnover and fracture rate. To our knowledge, changes in bone material strength after RYGB have not been explored. This study aimed to evaluate changes in factors influencing bone quality; bone material strength, aBMD and bone turnover markers, in a population with morbid obesity undergoing RYGB and whether these changes differed in participants with and without T2D. We also sought to assess factors associated with bone material strength and bone mineral density in obese subjects before and after RYGB.

METHODS

We examined 34 participants before and one year after RYGB, of whom 13 had T2D. Bone material strength index (BMSi) was evaluated by impact microindentation, aBMD and body composition by Dual energy X-ray absorptiometry, levels of bone turnover markers and calciotropic hormones were estimated from fasting serum samples. Participants with and without T2D were comparable before surgery, with the exception of glycosylated hemoglobin (HbA_1c).

RESULTS

Preoperatively, BMSi was inversely associated with BMI, β_unadjusted -1.1 (-1.9 to -0.28), R²=0.19, p=0.010, and this association remained significant after adjusting for age and gender. After RYGB the participants had lost a mean±SD of 33.9±10.9kg, 48.7±14.2 % of total body fat, increased physical activity, unchanged vitamin D levels, and all but one of the 13 participants with T2D were in diabetes remission. BMSi increased from 78.1±8.5 preoperatively to 82.0±6.4 one year after RYGB, corresponding to an increase of 4.0±9.8 in absolute units or 6.3±14.0 %, p=0.037. The increase was comparable in participants with and without T2D. In subjects with T2D, a larger decrease in HbA_1c was associated with a larger increase in BMSi β_unadjusted -9.2 (-16.5 to -1.9), R²=0.47, p=0.019. Bone turnover markers (CTX-1 and PINP) increased by 195.1±133.5 % and 109.5±70.6 %, respectively. aBMD decreased by 3.9±5.5 % in the lumbar spine, 8.2±4.6 % in the femoral neck, 11.6±4.9 % in total hip and 9.4±3.8 % in total body.

CONCLUSION

Our findings indicate that bone material strength improves despite an increase in bone turnover and a decrease in aBMD one year after RYGB. Trends were statistically comparable in participants with and without T2D. However, improved glucose control was associated with improved bone material strength in participants with T2D.

Anemia following Roux-en-Y gastric bypass for morbid obesity; a 5-year follow-up study

OBJECTIVES

Patients are at risk of anemia post Roux-en-Y gastric bypass (RYGB). We sought to determine the prevalence of anemia and related nutritional deficiencies 5 years after RYGB and to evaluate adherence to nutritional supplements with iron, vitamin B12, and folate.

MATERIAL AND METHODS

Patients operated with RYGB 2004-2006 were eligible for evaluation. Blood samples were collected and use of nutritional supplements was recorded preoperatively, and at outpatients' consultations 1, 2, and 5 years postoperatively. Of 203 patients operated, 184 (91%) completed the 5 year follow-up and were included in the study. Of these, 97% had valid measurements of hemoglobin both at baseline and after 5 years.

RESULTS

During the 5 years after RYGB, the prevalence of anemia increased from 4% preoperatively to 24% in females, and from 0% to 7% in males. Ferritin levels decreased gradually in both genders. Iron deficiency increased from 6% preoperatively to 42% at 5 years in females, and from 0% to 9% in males. Vitamin B12 deficiency was not altered while folate deficiency decreased from 10% preoperatively to 1% at 5 years. Five years after surgery 25% reported the use of supplements with iron, while 83% used vitamin B12 and 65% used multivitamins with folate.

CONCLUSIONS

We observed a long-term increase in anemia and iron deficiency after RYGB in both genders, but most pronounced in women. Our postoperative protocol for prevention of vitamin B12 and folate deficiencies appear acceptable. Iron status and iron supplementation seems to need stronger emphasis during follow-up after RYGB.

A novel technique of Roux-en-Y gastric bypass reversal for postprandial hyperinsulinemic hypoglycaemia: A case report

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Postprandial hypoglycemia may be a serious adverse effect following Roux-en-Y gastric bypass surgery.

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Most patient can be treated with diet and pharmacological agents, but some patients need surgical reversals.

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This Roux-en-Y gastric bypass reversal alleviates severe postprandial hyperinsulinaemic hypoglycaemia.

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The technique retains some component of rapid transit of food into a shorter alimentary limb in an attempt to reduce weight regain.

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This new surgical procedure also attenuates s-GLP-1 and s-insulin responses along with improved p-glucose.

Background

We describe an evaluation of the effects of partial Roux-en-Y gastric bypass (RYGB) reversal on postprandial hyperinsulinaemic hypoglycaemia, insulin and GLP-1 levels.

Case summary

A 37 year old man was admitted with neuroglycopenia (plasma–glucose 1.6 mmol/l) 18 months after RYGB, with normal 72 h fasting test and abdominal CT. Despite dietary modifications and medical treatment, the hypoglycaemic episodes escalated in frequency. Feeding by a gastrostomy tube positioned in the gastric remnant did not prevent severe episodes of hypoglycaemia. A modified reversal of the RYGB was performed. Mixed meal tests were done perorally (PO), through the gastrostomy tube 1 (GT1), 4 weeks (GT2) after placement and 4 weeks after reversal (POr), with assessment of glucose, insulin and GLP-1 levels.

Results

Plasma–glucose increased to a maximum of 9.6, 5.4, 6.5 and 5.8 mmol/l at the PO, GT1, GT2 and POr tests respectively. The corresponding insulin levels were 2939, 731, 725 and 463 pmol/l. A decrease of plasma–glucose followed: 2.2, 3.0, 3.9 and 2.9 mmol/l respectively and insulin levels were suppressed at 150 min: 45, 22, 21 and 14 pmol/l, respectively. GLP-1 levels increased in the PO test (60 min: 122 pmol/l, 21 fold of basal), but was attenuated in the two latter tests (12–23 pmol/l at 60 min).

Conclusions

Reduction of plasma–glucose, insulin and GLP-1 excursions and symptoms were seen after gastric tube placement and partial RYGB reversal. This attenuation of GLP-1 response to feeding could reflect an adaptation to nutrients.

Application of the International Diabetes Federation and American Diabetes Association criteria in the assessment of metabolic control after bariatric surgery

The International Diabetes Federation (IDF) and the American Diabetes Association (ADA) have introduced specific criteria to define the 'optimization' of the metabolic state and glycaemic 'remission' of type 2 diabetes mellitus (T2DM) after bariatric surgery, respectively. Our objective was to assess the percentage of patients achieving these criteria. Data were collected for body mass index, glycaemic markers, lipids, blood pressure, hypoglycaemia and medication usage from 396 morbidly obese T2DM patients who underwent bariatric surgery in two centres and followed up for 2 years. At year 1, 14% of patients achieved the IDF criteria and 38% the ADA criteria, whereas at 2 years 8 and 9% satisfied these criteria, respectively. A relatively low proportion of patients achieved optimization of the metabolic state and T2DM remission. These patients may potentially benefit from the combination of bariatric surgery and adjuvant medical therapy to achieve optimal metabolic outcomes.