The risk of falling and fracturing bone does not disappear after patients with obesity and type 2 diabetes, which together rob bone strength and flexibility, achieve significant weight loss. That risk remains — unless they adopt weight-bearing exercises as part of their regular routine. 

Like two to three times a week, type-of-regular routine — activity that, up until this point, has likely been absent in patients' lives. So, it may not be welcome news. 

"When patients are heavier, they tend not to move too much," said Joseph Huffstutter, MD, a longtime rheumatologist with Arthritis Associates in Hixson, Tennessee. "The heavier you get, you don't want to move."

So, counseled experts, don't spring this information on patients post-weight loss. Do it as soon as the patient says, I want to lose the weight.

"There are many wonderful benefits of weight loss, but it can be a silent disease developing in the background," said Jocelyn R. Wittstein, MD, an associate professor of orthopedic surgery at Duke University in Durham, North Carolina. "[Physicians] have a duty to remind people" that if they lose a lot of weight and do not perform weight-bearing exercises, they won't know about their bone fragility "until a bone is broken." 

So, when someone is diagnosed with type 2 diabetes, they should start training then, even when they are still overweight. "Yes, pair training with the weight loss," she said. "It is the most important part of the exercise regimen, period."

Huffstutter agreed. "Weight-bearing exercises are critical," considering the longtime damage incurred from excess weight. 

That damage stems from nutritional deficiencies, endocrine and hormonal changes, and reduced mechanical loading, which, without stimulation, removes muscle mass. And of course, type 2 diabetes also inflicts damage, like degrading bone microarchitecture. Diabetes can induce osteoporosis; obesity can lead to sarcopenia. Diabetes can shorten bone size, including the cross-sectional areas of the femoral neck and trochanter. Even some medications taken for diabetes are linked to increased fracture risk, including SGLT-2is and the sulfonylureas.

The exercise advice extends to those patients on GLP-1s. The majority of patients quit taking GLP-1 medications within a year, and many regain the weight. Getting physical on a regular basis can help patients keep this weight off.

The dosage of the GLP-1 matters, Wittstein said, with regard to fracture risk. Weight loss doses of GLP-1s, when used without strength training, can lower bone mineral density, but when combined with strength training, there is a neutral effect on BMD. But when GLP-1s are prescribed for patients with diabetes, the therapy could protect against vertebral fractures.

What Happens to Bones 

Referring to someone he knows who lost weight, Huffstutter said, "Imagine strapping 100 pounds on your back." 

During the years a patient has had diabetes and obesity, the two diseases have essentially remodeled bone. Healthy bone building has been attenuated by the shortage of insulin, which is needed to kick-start the bone formation process. And obesity, besides driving the metabolic processes leading to insulin resistance, causes mitochondrial dysfunction by impairing energy-producing fatty acid oxidation. It is oxidation that saves muscles from breaking down.

Huffstutter said bone fragility stems from a lack of calcium, the core ingredient of bone. If the body isn't taking in enough calcium, it will take it from bone. Complicating this theft is the lack of vitamin D, which instigates calcium absorption from bone. Bones then weaken.

It is the osteoblasts, stimulated by mechanical stress, specific nutrients, and hormones, that begin the bone rebuilding process. If there is none or little weight-bearing activity, "there is no stimulation to create new bone," Huffstutter said.

So old bone isn't replaced. Wittstein said that without the bone rebuilding process, bone has lower density, "and later in life, patients will be at risk for osteoporosis and risk of fracture." 

Patients who lose muscle mass can increase their risk of sarcopenia.

The GLP-1s

Huffstutter said that of the 20 or so patients he sees a day, at least 15% are on a GLP-1. "And this is an arthritis clinic. [Fifteen percent] is a lot of patients."

Said the authors of a new perspective on GLP-1 therapies and exercise: "Although GLP-1 receptor agonists offer powerful new opportunities for losing weight, they do not diminish the manifold benefits of exercise and instead highlight the need to translate exercise's efficacy into effectiveness." 

Advice

Huffstutter said the resources are out there to help patients find a good exercise program. "What lacks is the motivation" to use them. But he acknowledged the difficulty that patients face. "If this were easy we would not be an obese nation."

A press release on that new perspective on GLP-1 therapies said "improving adherence is now the central challenge in translating exercise's proven benefits into real-world impact."

Wittstein and Huffstutter both said PCPs need to develop a professional network that can help patients figure out their best exercise approach. It might be easier for patients with osteopenia or osteoporosis to get help from a physical therapist by using ICD codes "like muscle weakness," Wittstein said. 

Of course, the easiest way to avoid bone fragility is to prevent it. Both experts advocated for hormone replacement therapy for women entering the perimenopausal stage of their lives. (Testosterone therapy for men has been linked with improved bone mineral density, but not necessarily a reduced rate of fractures.)

Wittstein said HRT improves bone mineral density, reduces the risk of fractures, and can prevent osteoporosis. "The longer the exposure, the more reduced the fracture risk." An older study out of Sweden said HRT can start several years after menopause, and still protect against hip fractures.

Huffstutter said whatever patients can do to work weight-bearing exercises into their routines is great. "Walking is great, a treadmill has a little more cushion." As for weight machines, he said patients should start with lighter weights. As patients get older, they could rupture a tendon. Patients need an exercise prescription, he said. "I will ask what resources they have."

Huffstutter pleaded with PCPs not to let patients with osteoporosis slip through the cracks: Notice dowager humps, consider scans for back pain, as a fragility fracture could be causing that discomfort. Get bone density measurements every 10 years. "Have something on the record."

Huffstutter reported having no relevant financial relationships. Wittstein is a consultant for Miach; reports ViewFi stock options and serves on its advisory board; and is an Arthrex paid speaker and a Vericel paid speaker.