Bone formation and maintaining healthy bones is a complex process. You may have experienced a bone fracture and you realize that healing takes time and often rehabilitation is needed to get the bone back to its normal function. This past couple of months I have noticed many articles and webinars talking about the relationship of bone disorders in patients with diabetes and this is why I am focusing today’s blog on this topic. Since it is an extensive topic I will do a second part in the subsequent blog.
The effects of diabetes on bone formation, structure, metabolism, quality and bone density are still being debated, however, there definitely seems to be some connection as witnessed in many research and observational studies.
There are multiple risk factors for all of us including those without diabetes. Most of us have heard of the condition referred to as osteoporosis and how the risk of falls and fractures increase as we age.
Risk factors consist of two categories, those that are modifiable (things we can change) and nonmodifiable (those that we can’t change).
Modifiable risk factors include (not all inclusive):
Cigarette smoking
Low body weight
Estrogen or androgen deficiency
Low calcium intake
Excess alcohol use
Inadequate physical activity
Medications
Chronic health conditions (renal disease, diabetes, inflammatory bowel disease)
Nonmodifiable risk factors include (not all inclusive):
Ethnicity (white race more frequent)
Aging
Sex (female > male)
Impairment of cognition (brain function)
Frailty and co-morbid diseases
Previous fracture or fracture of a first-degree relative
Possible explanations of how diabetes affects our bones is explained by many authors from around the world and deserves to be discussed with our health-care providers. The following are some thoughts for causation.
Increased bone fragility
Observational studies in patients with type 1 & type 2 diabetes have shown that there is an increase risk of hip and other fractures and they suggest that bone fragility could be the cause. As well, fracture healing has been shown to be prolonged in those with diabetes. As I said at the beginning, debate on this topic still exists. There are other studies that have shown the prevalence and incidence of vertebral fractures was not higher in men aged 65 and older either with or without diabetes. This bone fragility can happen as a result of alterations in bone metabolism and structure.
Bone metabolism
In both types of diabetes bone turnover is usually low. This means that the cells called that form new bone (osteoblasts) are low, yet the cells which break down bone (osteoclasts) tissue are normal or reduced. Under normal circumstances, there is a balance between bone resorption (ie breakdown) and bone formation by the osteoblasts. It is thought that hyperglycemia (high blood sugars) may cause an increase in the urine excretion of calcium (a mineral need for bone formation) which leads to inhibition of bone formation (bone can’t be formed). Other reasons do exist but are beyond the scope of today’s blog purpose.
Bone density
Bone density if a measure of the amount of minerals, mainly calcium and phosphorous, contained in a certain volume of bone. In patients with type 1 diabetes this is usually found to be lower but normal or increased in patients with type 2 diabetes.
Some studies have shown that in well controlled type 1 patients there are no changes in bone mineral density. If this is the case, just one more reason for us to try and maintain our diabetes in a healthy state.
Another consideration is the age at which type 1 diabetes was diagnosed since this might result in decreased peak bone mass during the growing years.
Increased cortical porosity
Cortical bone is the dense outer surface of the bone that forms a protective layer around the internal cavity. This type of bone makes up 80% of our skeletal mass and it is imperative to body structure and weight bearing. Research has suggested that there is a deficit in this cortical bone, leading to incread areas of the bone which is not occupied by bone tissue (cortical porosity) and contributing to fracture risk in type 2 diabetes.
Thus from reviewing the above information we can conclude that bone disorders and increase risk of osteoporosis and fractures is a combination of features such as duration of disease, age of onset, poor diabetes control, an impairment of bone quality and side effects of medications.
Ever so often there is a news bulletin that tells us that some medication has shown to increase the risk of falls so as a pharmacist I can’t finish without talking about the diabetes medications used to treat type 2 diabetes.
Medications for type 2 diabetes are abundant as many of you know. Each class of antidiabetics acts through a distinct biological pathway which may the reason for varying degrees of adverse effects from the various medications. I did come across a nice article published in 2017 written as a review article of the effects of type 2 diabetes therapies on bone metabolism. The conclusion can be summarized as follows:
1)T2DM patients have an increased risk of fragility fractures which are not often detected by normal bone density testing procedures.
2)The risk is multifactorial and antidiabetic medications may have an impact on bone metabolism.Updated literature in 2019 (UpToDate) suggest the drug class Thiazolidinediones (ie, pioglitazone, etc) and sodium-glucose co-transporter 2(SGLT) inhibitors (ie canaglifozin,etc) have been associated with an increased risk of fracture. Use these agents with extreme caution and avoid if at all possible in patients already at an extremely high risk of fracture.
3)it is only after prolonged exposure that drug effects on fractures can be determined so evidence takes some time. Enough evidence has to be available to make proper decisions.
4)Physicians should always take into consideration the risk of falls and fractures of their patient and prescribe accordingly.
An often overlooked complication of diabetes is that of bone disorders. I hope you have benefited from today’s information and that it started you to think about maintaining healthy bones and taking steps to decrease your chance of fractures. I will continue this discussion in the next blog so please stay tuned.
#bonedisease&diabetes
References:
1. Bone Disease in diabetes mellitus- UpToDate accessed on December 30th,2020
2. Review article: effects of type 2 diabetes therapies on bone metabolism- accessed on January 2nd,2021
3. Osteoporosis Among Patients with Diabetes: An Overlooked Disease accessed on January 2nd,2021
As always the information provided here is not intended to replace information provided by your health-care providers. The purpose is to educate those living with diabetes.