Bariatric Surgery - Can We Predict Remission Of Diabetes?

One of the most important benefits of bariatric surgery (especially gastric bypass and sleeve gastrectomy) is its ability to improve the control of type 2 diabetes, often to the point where type 2 diabetes actually goes into remission after surgery.  Not everyone with type 2 diabetes who has bariatric surgery will experience remission - about 70-80% of patients having gastric bypass and about 50-60% of patients having sleeve gastrectomy will experience remission.  Ideally, we would be able to predict the likelihood of diabetes remission before the surgery is done, as this is arguably one of the most important potential benefits of bariatric surgery.

A recent study tried to answer this question using a scoring system called the DiaRem Score, which looked at at 4 preoperative variables amongst a group of 407 patients who underwent gastric bypass surgery:

• age
• need for insulin 
• diabetes medication use (points assigned varied by type of medication)
• hemoglobin A1C (a blood test which is a 3 month report card of diabetes control)

They found that this score, which is based on the above 4 variables, was highly predictive of who went into remission from their type 2 diabetes and who did not.

Other scoring systems and variables have been looked at as well.  Other variables that stands out in the literature are a shorter duration of diabetes, and preoperative serum C peptide level, which is a marker of a person's ability to produce insulin.

It is exciting to know that as we learn more about bariatric surgery, that we can become better at predicting who may benefit from a diabetes standpoint.  However, a word of caution - longer term studies suggest that for people who do enjoy diabetes remission after bariatric surgery, the diabetes recurs in about 50% of these people by 5 years post op.  While there is still certainly a health benefit to being free of diabetes for a number of years, it is important to remember that the diabetes can return and must be screened for regularly and lifelong.

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www.drsue.ca © 2017

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Pregnancy After Bariatric Surgery - How Long Should You Wait?

After bariatric surgery, it is recommended to wait at least 12-18 months (with some guidelines recommending to wait two full years) before considering pregnancy.  This is because rapid weight loss and a higher risk for nutritional deficiencies occurs during this phase, which may be a poor environment for fetal development. However, a recent study suggests that waiting two years may not be enough.

The study, published in JAMA Surgery, looked at data from women and their infants in Washington state who had had bariatric surgery (n=1859), and compared them to women and their infants who had not had bariatric surgery (n=8437).  They found that babies who were born to mothers who had had bariatric surgery had a 57% higher risk of prematurity, 25% higher risk of needing to be admitted to the NICU, 93% higher risk of being small for gestational age.

However, when 4 years or more had elapsed since bariatric surgery, the risk of these outcomes was lower when compared to women where 2 years or less had elapsed.  Specifically, the risk for babies born less than 2 years after bariatric surgery was 48% higher for prematurity and 54% higher for NICU admission, compared to babies born to mothers where 4 years or more had elapsed (the difference for being small for gestational age was not significant). For babies born in the 2-4 year window after bariatric surgery, the authors note that the prevalence of prematurity and NICU admission was not meaningfully different from babies born to women who had not had bariatric surgery.

So how do we interpret these data? Well, we already knew that the risks identified in this study exist for babies born to mothers after bariatric surgery, but we need to remember that there are benefits to pregnancy outcomes after bariatric surgery as well - for example, less babies born large for gestational age, less labor and delivery complications, lower risk of C section birth, lower risk of gestational diabetes and high blood pressure in pregnancy.  However, based on these data, it may be better to wait even longer than two years after bariatric surgery before conceiving.

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www.drsue.ca © 2016

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Duodenal Mucosal Resurfacing for Treatment of Type 2 Diabetes?

Our knowledge and understanding about the role of gut hormones in type 2 diabetes continues to grow, as we get a better understanding of the mechanisms involved in the often dramatic improvement in diabetes that is seen after bariatric surgery.  In gastric bypass surgery, we know that at least one of the mechanisms involved is food literally bypassing the first segment of the small intestine, called the duodenum.  This effect may be seen because food is more rapidly delivered to the intestine further down, causing a more powerful release of hormones from the more distal intestine (called the hindgut hypothesis).  However, there may also be an as yet unidentified hormone (or hormones) secreted by the first part of the gut that have an antidiabetic effect, and by having food skip over this part of the gut, this mystery antidiabetic hormone is not released, thereby improving blood sugar control (called the foregut hypothesis).  We do know that the surface of the duodenum in a person with diabetes is altered, with a sort of overgrowth of cells in the duodenal mucosal (called hypertrophy and hyperplasia).

For believers of the foregut hypothesis, a novel approach called Duodenal Mucosal Resurfacing (DMR) is now being studied to see if diabetes control can be improved by doing a sort of 'thinning out' of the lining of the upper part of the intestine.

The first human study of DMR, recently published in the journal Diabetes Care, performed the DMR procedure in 39 patients with type 2 diabetes.  They found an improvement in diabetes control at 6 months post procedure, with greater improvement in those who had a longer segment of the duodenum ablated than those that had a shorter segment treated. Improvement in blood sugars was seen as soon as 1-2 weeks after the procedure, despite no restrictions in diet or calorie intake being recommended.  The improvement in diabetes control was not as powerful as what is seen with gastric bypass surgery, suggesting that there are many additional elements at work in gastric bypass surgery.  The authors also noted that there was some erosion of the improvement in diabetes control at 6 months, so certainly larger and longer studies need to be done to understand what the effect of this procedure is over the long term. There was little weight loss in this study (only a few kg), so the DMR does not hold promise as a weight management strategy.   The procedure was well tolerated overall, though there were three cases of duodenal stenosis that were treated with balloon dilatation.  The authors noted no signals for malabsorption (eg no calcium abnormalities or iron deficiency anemia), but this would need to be evaluated carefully in long term studies as well.

It will be interesting to see further study of the DMR procedure.

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New 'Real-World' Obesity Clinical Practice Guidelines

It is an unfortunate fact that despite the high prevalence of overweight and obesity in our society, most health care professionals receive little training in obesity medicine.  I am asked by colleagues just about every day: ‘How do I treat my patient who struggles with excess weight?’  Health care providers often feel lost in this arena.  

There are a number of obesity management guidelines that try to guide the care of people with obesity, but they often do not provide a consensus on a clear and concise approach to management or treatment goals.

Good news! The American Association of Clinical Endocrinologists and American College of Endocrinology have produced a new set of Clinical PracticeGuidelines for obesity that they describe as an evidence based, real-world approach, that gives health care providers practical, straightforward, and tangible algorithms for diagnosis, assessment, and management of people with excess weight.

The theme of these guidelines (which I fully agree with) is that management of obesity is not about the numbers on the scale, but about improving overall health and well being.

The approach to diagnosis and management in these guidelines are nicely packaged into a handful of algorithms and tables that you can access here.  Some of the highlights:

1.  The diagnosis of obesity is not just about the numbers on the scale.  They break down the obesity diagnosis into two components: the anthropometric component (numbers: BMI, waist circumference), and the critically important clinical component (complications of the excess weight, of which they have included a convenient checklist of things to look for and how to screen for them).

2.  There is a beautiful table that lists how much weight loss is recommended to improve any particular complication of obesity (eg 5-15% for type 2 diabetes, 5-15% or more for polycystic ovary syndrome, 7-11% or more for obstructive sleep apnea).

3.  They break down lifestyle treatment into three components: meal plan, physical activity, and behavior modification.  They review pros and cons to different types of diets and where evidence exists for improvement of parameters of health (while emphasizing that the dietary approach needs to be individualized to each patient).

4.  They review pros and cons of medications to treat obesity (note that only two of the medications reviewed are available in Canada – namely, liraglutide and orlistat), along with clinical features that may favor the use of one antiobesity medication over another.

In the spirit of focusing on treating to improve weight-associated health complications rather than focus on numbers on the scale, they suggest more intensive treatment approaches (eg medication or bariatric surgery) in situations where complications of obesity already exist.  Personally, I am inclined to favor a more proactive approach, not only looking at these treatment options to improve upon existing complications of obesity, but also to prevent these complications from developing in the first place.

Overall, these guidelines and nicely packaged tables and algorithms provide a great framework to help health care professionals with a real-world approach to obesity management.  Check it out!

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www.drsue.ca © 2016

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Diabetic Ketoacidosis After Bariatric Surgery in Type 2 Diabetes

Diabetic ketoacidosis (DKA) is a potentially life threatening complication that can occur in people with diabetes.  While we typically associate DKA with type 1 diabetes, it can also rarely happen in type 2 diabetes.   DKA can occur if insulin levels are low, and can be precipitated by a stress on the body, including infection or illness, dehydration, heart attack, and so forth.

A case series was recently published, describing four cases of DKA after bariatric surgery, in three people with type 2 diabetes.   The average time to presentation of DKA was 13 days after surgery (range 3-27 days). All patients were on insulin prior to surgery.  Factors contributing to DKA included omission of insulin and dehydration.

One of these patients was on canagliflozin prior to surgery.  Canagliflozin is a medication in a class of type 2 diabetes medications called SGLT-2 inhibitors, which slightly increase the risk of DKA, particularly if insulin is not taken as directed by the health care team.  Also, if a person taking an SGLT2 inhibitor becomes unwell or dehydrated for any reason while taking the medication, this increases the risk of DKA.  The DKA case in the patient on canagliflozin in this study also had omission of insulin and poor food intake post operatively as contributory factors.

These findings teach us the following:

1.  Patients with type 2 diabetes having bariatric surgery need to be followed closely postoperatively, with meticulous attention to blood sugars and insulin needs.  Some people with type 2 diabetes who were on insulin before surgery do not require insulin after surgery, but others do.   There must also be a low threshold for concern if they become dehydrated due to difficulty tolerating oral intake.

2.  SGLT2 inhibitors should be stopped prior to bariatric surgery (possibly before starting any low calorie diet plan), and if there is still a need for medication to control blood sugar post op, it should not be restarted until the patient is eating and drinking well after discharge home from surgery.

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Bariatric Surgery For Type 1 Diabetes?

In parallel with the obesity epidemic in our general society, so too do many type 1 diabetics struggle with excess weight.  I am often asked whether patients with type 1 diabetes could benefit from bariatric surgery.

First, a review on the difference between Type 1 vs Type 2 diabetes:

• Type 1 diabetes is an autoimmune condition, where the immune system mounts a response against the pancreas, causing the pancreas to stop producing insulin.  Type 1 diabetics require insulin as treatment.
• Type 2 diabetes is a condition where the body is resistant to the effects of insulin.  This means that the pancreas has to work harder to make enough insulin to put sugar into cells for use as energy.  Over time, the overworked pancreas gets tired, its ability to produce enough insulin to control blood sugars declines, and diabetes develops. Some Type 2 diabetics are treated with lifestyle modification alone, some with pills or injectable medication, and some require insulin because their pancreas is too tired to make the insulin they need.

About 10% of diabetics have type 1 diabetes, and 90% have type 2 diabetes.  Traditionally, we used to think of type 1 diabetes being the kind of diabetes that has onset in thin kids or young adults, and type 2 diabetes as having onset in people with obesity later in life.  It turns out that type 2 diabetes can come on in childhood (the youngest type 2 diabetic recorded in Canada was 5 years old at diagnosis), and type 1 diabetes can sometimes have onset later in life.  Some people with type 2 diabetes have an ideal body weight, and some people with type 1 diabetes struggle with obesity.

There is lots of evidence to support the efficacy of bariatric surgery (especially gastric bypass surgery and sleeve gastrectomy) to improve control of type 2 diabetes, or even send it into remission (meaning the type 2 diabetes goes away - though it may reoccur later).

For type 1 diabetes, there is very little data.  However, a recent review summarizes the literature available for us, and what it found is that while bariatric surgery can be of benefit to help people with type 1 diabetes lose weight and reduce risk factors for heart disease, diabetes control does not seem to improve overall.

So, while bariatric surgery can be an appropriate treatment strategy for type 2 diabetes in people who struggle with obesity, the evidence does not support it for the improvement of diabetes control in type 1 diabetes.

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Does Gastric Bypass Surgery Increase Energy Burn?

We know that Roux-en-Y gastric bypass surgery is effective to induce weight loss, causing an average weight loss of about 40% of total body weight.  How this actually happens is still far from completely understood.   Many mechanisms are likely at play, but one of the most hotly debated is whether energy burn (called energy expenditure) goes up, down, or does not change after gastric bypass surgery.

We have recently published the results of our randomized, controlled clinical trial in gastric bypass patients, to add to our understanding of this complex area.

In this trial, conducted at the University of Copenhagen and published in the International Journal of Obesity, we enrolled 28 patients, and placed them on a low calorie diet (1000 kcal/day) in preparation for their gastric bypass surgery.  Patients were randomized to have surgery either 8 weeks or 12 weeks after the start of the low calorie diet, such that we could compare them just before the second group had surgery.  (This protocol enabled us to use a 'pair-fed' control model, as there have been criticisms of other studies comparing post surgical patients to control groups who are eating totally differently, not on a low calorie diet, and not on a negative weight trajectory.)  We then repeated testing on the entire group at 1.5 years post surgery.

We found that at 3 weeks postoperatively, patients had lower body composition-adjusted 24 hour and basal energy expenditure compared to those who had not yet had their surgery.  However, at the 1.5 year mark, patients' energy expenditure was not different compared to their own preoperative values.   We also found that surgery increased the postprandial response to many hormones, including GLP-1, PYY, bile acids, and FGF-19.  Decreases in appetite were particularly associated with increased GLP-1, increased PYY, and decreased ghrelin.

So, our study suggests that the decrease in weight seen after gastric bypass surgery is not caused by an increase in energy expenditure, but that weight loss is more likely to be mediated by hormonally-induced changes in appetite.

An enormous and heartfelt thank you to my ex-PhD student (now postdoc!) Dr Julie Berg Schmidt, and all of my dear colleagues at the University of Copenhagen, for years of fantastic collaboration to bring this study to fruition!  Stay tuned for many more publications stemming from this trial.

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www.drsue.ca © 2015

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