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Do SGLT-2 Inhibitors Change Fat Metabolism?

sharma-obesity-blood-sugar-testing2Since the introduction of SGLT-2 inhibitors (“gliflozins” or “glucoretics), as an insulin-independent treatment for type 2 diabetes, that works by blocking glucose reabsorbtion in the kidney┬áresulting in loss of glucose (and calories) through the kidney, much has been written about the (albeit modest) weight loss associated with this treatment.

Several studies have documented that the weight loss leads to a change in body composition with an often significant reduction in fat mass.

Now, Giuseppe Daniele and colleagues, in a paper published in Diabetes Care, show that treatment with these compounds may enhance fat oxidation and increase ketone production in patients with type 2 diabetes.

The researchers randomized 18 individuals with type 2 diabetes to dapagliflozin or placebo for two weeks.

As expected, dapagliflozin reduced fasting plasma glucose significantly (from 167  to 128 mg/dL).

It also increased insulin-stimulated glucose disposal (measured by insulin clamp) by 36%, indicating a significant increase in insulin sensitivity.

Compared to baseline, glucose oxidation decreased by about 20%, whereas nonoxidative glucose disposal (glycogen synthesis) increased by almost 50%.

Moreover, dapagliflozin increased lipid oxidation resulting in a four-fold increase in plasma ketone concentration and and a 30% increase in fasting plasma glucagon.

Thus, the authors note that treatment with dapagliflozine improved insulin sensitivity and caused a shift from glucose to lipid oxidation, which, together with an increase in glucagon-to-insulin ratio, provide the metabolic basis for increased ketone production.

While this may explain the recent observation of a greater (albeit still rather rare) incidence of ketoacidosis with the use of these compounds, these findings may also explain part of the change in body composition previously noted with SGLT-2 treatment.

While this still does not make SGLT-2 inhibitors “weight-loss drugs”, there appears to be more to the fat┬áloss seen with these compounds than just the urinary┬áexcretion of glucose.

@DrSharma
Edmonton, AB

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Metformin Attenuates Long-Term Weight Gain in Insulin-Resistant Adolescents

metformin-300x217The biguanide metformin is widely used for the treatment of type 2 diabetes. Metformin has also been shown to slow the progression from pre to full-blown type 2 diabetes. Moreover, metformin can reduce weight gain associated with psychotropic medications and polycystic ovary syndrome.

Now, a randomised controlled trial by M P van der Aa and colleagues from the Netherlands, published in Nutrition & Diabetes suggests that long-term treatment with metformin may stabilize body weight and improve body composition in adolescents with obesity and insulin resistance.

The randomised placebo-controlled double-blinded trial included 62 adolescents with obesity aged 10ÔÇô16 years old with insulin resistance, who received 2000ÔÇëmg of metformin or placebo daily and physical training twice weekly over 18 months.

Of the 42 participants (mean age 13, mean BMI 30), BMI was stabilised in the metformin group (+0.2 BMI unit), whereas the control group continued to gain weight (+1.2 BMI units).

While there was no significant difference in HOMA-IR, mean fat percentage reduced by 3% compared to no change in the control group.

Thus, the researcher conclude that long-term treatment with metformin in adolescents with obesity and insulin resistance can result in stabilization of BMI and improved body composition compared with placebo.

Given the rather limited effective options for addressing childhood obesity, this rather safe, simple, and inexpensive treatment may at least provide some relief for adolescents struggling with excess weight gain.

@DrSharma
Edmonton, AB

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Zafgen Abandons Belanorib Program But Continues Exploring MetAP2 Inhibitor For Obesity

sharma-obesity-insulin-injectionRegular readers may recall previous posts on the novel anti-obesity compound belanorib, a MetAP2 inhibitor that showed remarkable weight loss efficacy both in patients with Prader-Willi Syndrome as well as hypothalamic obesity.

Unfortunately, as noted before, several cases of venous thromoboembolisms led to a halt of ongoing trials during which the company (Zafgen) sought to better understand the possible mechanism for this serious adverse effect and explore the possibility of implementing a risk mitigation strategy.

As announced by the company in a press release earlier this week,

“Following its discussions with the FDA and review of other considerations, Zafgen has determined that the obstacles, costs and development timelines to obtain marketing approval for beloranib are too great to justify additional investment in the program, particularly given the promising emerging profile of ZGN-1061. The Company is therefore suspending further development of beloranib in order to focus its resources on ZGN-1061.”

The press release also describes the new compound ZGN-1061 as a,

“…fumagillin-class, injectable small molecule second generation MetAP2 inhibitor that was discovered by Zafgen’s researchers and has been shown to have an improved profile relative to previous inhibitors in the class.┬áLike other MetAP2 inhibitors that have shown promise in the treatment of metabolic diseases including severe and complicated obesity, ZGN-1061 modulates the activity of key cellular processes that control the body’s ability to make and store fat, and utilize fat and glucose as an energy source.┬áZGN-1061 is also anticipated to help reduce hunger and restore balance to fat metabolism, enabling calories to once again be used as a productive energy source, leading to weight loss and improved metabolic control. ZGN-1061 has an emerging safety profile and dosage form that are believed to be appropriate for the treatment of prevalent forms of severe and complicated obesity, and is currently in Phase 1 clinical development. Zafgen holds exclusive worldwide rights for the development and commercialization of ZGN-1061.”

According to the press release,

“The compound has similar efficacy, potency, and range of activity in animal models of obesity as beloranib, but displays highly differentiated properties and a reduced potential to impact thrombosis, supporting the value of the compound as a more highly optimized MetAP2 inhibitor.”

Screening of patients for a Phase 1 clinical trial evaluating ZGN-1061 for safety, tolerability, and weight loss efficacy over four weeks of treatment is currently underway.

@DrSharma
Edmonton, AB

Disclaimer: I have served as a consultant to Zafgen.

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POMC Mutation Obesity Responds To Melanocortin-4 Receptor Agonist

sharma-obesity-hypothalamusMelanocyte-stimulating hormone (a-MSH), which is produced from the hormone precursor proopiomelanocortin (POMC) and acts on the hypothalamic melanocortin-4 receptor, plays a key role in the regulation of satiety and energy expenditure.

In very rare instances, mutations of the gene coding for POMC can cause severe early onset obesity characterised by increased appetite. Due to other effects of POMC deficiency, patients will present with pale skin, red hair and clinical signs of hypocortisolism.

Now, a paper by Peter K├╝hnen and colleagues published in the New England Journal of Medicine, shows that treating patients with the melanocortin-4 receptor agonist, setmelanotide, can result in significant reduction in appetite and body weight.

The open-label study was performed in two adult patients with POMC deficiency, in cooperation with Rhythm Pharmaceuticals, which provided the study medication and regulatory support.

Both patients weighed around 150 Kg with marked hyperphagia and both responded to treatment with a substantial reduction in appetite and dramatic weight loss of over 20 Kg over 12-13 weeks.

After a brief interruption, one patient was again treated for 42 weeks, ultimately losing 51 kg (32.9% of her initial body weight).

As the authors note,

“Setmelanotide appeared to completely reverse hyperphagia, leading to impressive weight loss and normalization of insulin resistance. More important, both patients reported a dramatic improvement in their quality of life after the initiation of setmelanotide therapy. Moreover, the substantial and ongoing reduction in body weight was similar to the changes observed after leptin administration in patients with leptin deficiency.”

Over all the treatment was well tolerated with no major adverse effects.

While these observations were made in very rare patients with documented POMC deficiency, these findings may have broader implications for individuals with more common “garden-variety” obesity.

“Both patients described here had very high leptin levels before treatment, suggesting leptin resistance. In patients with proopiomelanocortin deficiency, the leptin signal is probably not properly transduced into anorexigenic responses, given the lack of melanocyte-stimulating hormone. Setmelanotide substitutes for melanocyte-stimulating hormone and binds at its receptor, thus overcoming leptin resistance. On the basis of the observation that obese patients without known genetic abnormalities have severe leptin resistance and regain weight owing to a post-dieting increase in appetite, we speculate that setmelanotide may also be effective in nongenetic forms of obesity.”

Appropriate studies in patients with non-POMC deficient obesity are currently underway.

@DrSharma
Atlanta, GA

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Arguments For Calling Obesity A Disease #5: Access To Care

sharma-obesity-doctor-kidContinuing in my miniseries on arguments in favour of calling obesity (defined as excess or abnormal fat tissue that impairs health) a disease, I turn to the perhaps most important reason of all – access to care.

Currently, few health care systems feel obliged to provide individuals presenting with obesity treatment for their condition (beyond a few words of caution and simplistic advise to simply eat less and move more).

Most health plans do not cover treatments for obesity, arguing that this is simply a lifestyle issue.

In some countries (e.g. Germany), health insurance and health benefit plans are expressly forbidden by law to cover medical treatments for obesity.

Although long established as the only evidence-based effective long-term treatment for severe obesity, many jurisdictions continue to woefully underprovide access to bariatric surgery, with currently less than 4 out of 1,000 eligible patients receiving surgery per year in Canada.

Pretty much all of this can be blamed on one issue alone – the notion that obesity is simply a matter or personal choice and can be remediated by simple lifestyle change.

Declaring obesity a disease can potentially change all of this.

As a disease in its own right, health care systems can no longer refuse to provide treatments for this condition.

In the same manner that no health system or insurance plan can refuse to cover treatments for diabetes or hypertension, no health system or insurance plan should be able to deny coverage for treatments for obesity.

As a chronic disease, obesity care must now be firmly integrated into chronic disease management programs, in the same manner that these programs provide services to patients with other chronic diseases.

How long will it take before this becomes accepted practice and funding for obesity treatments rises to the level of funding currently available for treating other chronic diseases?

That, is anyone’s guess, but no doubt, declaring obesity a disease finally puts patients living with this condition on an equal footing with patients living with any other chronic disease.

@DrSharma
Edmonton, AB

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