"As I get older, I seem to catch colds more easily and they take longer to recover." Many people in their 40s or older experience these age-related changes in their physical condition. However, if you also suffer from diabetes, you need to be especially careful about a weakened immune system. This is because the natural weakening of immune function due to aging, combined with the chronic disease of diabetes, doubles your risk of infection.
In this article, we will explain why the combination of aging and diabetes weakens the immune system, infectious diseases that require particular attention, and points to note about blood sugar control that are unique to the elderly.
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Reasons why "aging + diabetes" weakens the immune system
Cause 1. Blood sugar reduces immune cell function
The reason diabetes weakens the immune system is due to high blood sugar levels. High blood sugar levels adversely affect the function of immune cells that protect our bodies, particularly neutrophils. Neutrophils are central immune cells that fight against bacteria, fungi, and other invading organisms (innate immunity).
It is known that high blood sugar reduces important neutrophil functions, specifically the following four:
- Decreased migration ability: When an infection occurs, neutrophils need to rush to the scene (site of infection) quickly. High blood sugar reduces this migration ability.
- Decreased phagocytic ability: When neutrophils arrive at the scene, they neutralize the pathogens by engulfing them (phagocytosing them). High blood sugar also weakens this "ability to ingest."
- Decreased bactericidal ability (killing power): After ingesting bacteria, neutrophils produce reactive oxygen species (respiratory burst) and other substances to kill the bacteria within the cell. High blood sugar levels reduce the ability to produce this reactive oxygen species, weakening the ability to kill bacteria.
- Inhibition of NETs formation: Neutrophils have a function called "NETs," in which they release their nuclei (chromatin) outside the cell like a net, trapping and killing bacteria. It has been reported that neutrophils exposed to high concentrations of glucose are unable to form these NETs effectively, making it easier for bacteria to survive.
Source: Journal of the Japanese Society of Chemotherapy | Abnormal neutrophil function in diabetic patients
Cause 2. "Immunosenescence" due to aging
Diabetes is not the only reason for a decline in immunity. Aging itself also causes immune function to deteriorate. This is called "immunosenescence," and refers to a condition in which the immune system's natural mechanisms for eliminating foreign invaders (non-self) and for suppressing excessive inflammatory responses both decline with age.
As a result, elderly people are not only more susceptible to infectious diseases (immune disease), but are also more likely to fall into a state of "chronic inflammation" in which mild inflammation persists in the body.When this is combined with a weakened immune system caused by diabetes, the risk increases even further.
Source: Thrombosis and Hemostasis | Immune aging and chronic inflammation
Cause 3. Effects of diabetes complications
What makes diabetes scary is not only the weakening of immune function due to hyperglycemia itself (Cause 1), but also the "complications" caused by long-term hyperglycemia, which are deeply related to the worsening of infectious diseases.
For example, if complications such as arteriosclerosis cause blood flow problems, not enough blood reaches the infected area, which means that not only oxygen and nutrients, but also neutrophils and administered antibiotics are less likely to reach the site. Furthermore, as neuropathy progresses, pain is less likely to be felt when a wound is formed in the foot, leading to delayed detection of the wound and increased risk of bacterial invasion and serious complications (e.g., diabetic foot disease).
Source: Diabetes | Characteristics of infectious diseases in diabetic patients and their countermeasures
Infectious diseases that elderly patients with diabetes should be particularly careful of
Due to a weakened immune system, elderly people with diabetes need to be careful of various infectious diseases. The infectious diseases that elderly people with diabetes should be careful of are as follows:
- urinary tract infection
- respiratory infections
- biliary tract infection
- Skin infections
- Periodontal disease, etc.
The problem is that not only are people susceptible to diabetes, but they are also more likely to develop severe infections than those without it. It is said that people with particularly poor blood sugar control have a weaker resistance to bacteria and fungi, making them more susceptible to serious infections. Furthermore, they are prone to developing infections in unusual locations, which can make diagnosis difficult. Examples of infections include malignant otitis externa, emphysematous pyelonephritis, renal abscess, emphysematous cholecystitis, necrotizing fasciitis, rhinocerebral mucormycosis, and Fournier's gangrene.
Source: Diabetes Information Center | Talking about diabetes and infectious diseases
[Countermeasures] Blood sugar control unique to elderly people with diabetes
The goal is to "correct hyperglycemia" and "avoid hypoglycemia"
While blood sugar control is essential for preventing infection, treating diabetes in the elderly requires a different approach than that for younger people. The goal is to thoroughly correct hyperglycemia while simultaneously avoiding hypoglycemia.
As people age, they are more susceptible to hypoglycemia due to medications that are too effective or reduced food intake. Furthermore, even if they develop hypoglycemia, they often do not show typical symptoms (sweating, palpitations), but instead manifest as atypical symptoms such as feeling lightheaded or unsteady, making it difficult to recognize. Severe hypoglycemia itself is a risk factor for dementia, falls, fractures, cardiovascular disease, microangiopathy, and death.
Source: Heart | Characteristics and Treatment of Diabetes in the Elderly
Keeping an eye on geriatric syndromes that often occur together
When treating elderly people, focusing only on blood glucose levels can lead to misunderstandings of the underlying condition. It is also necessary to pay attention to the overall "geriatric syndrome" that is likely to occur together, such as decline in cognitive function, decline in ADL (activities of daily living), frailty, depression, and risk of falls.
For example, it is not realistic to ask someone with impaired cognitive function to perform complex blood glucose measurements or insulin injections. It is important to consider the person's living situation, support system, and other concurrent illnesses, and select a treatment method that can be continued safely and comfortably.
Source: Heart | Characteristics and Treatment of Diabetes in the Elderly
summary
The combination of aging and diabetes significantly increases the risk of infection. In order to combat the risk of infection, it is important to understand that daily blood sugar control is directly linked to maintaining immune function.
However, for elderly people, the goal is not just to drastically lower hemoglobin A1c (HbA1c) levels. Safe control that "avoids hypoglycemia" is the top priority. It is important to notice any changes in your physical condition early on, such as "I've been catching colds more often recently" or "my blood sugar levels are unstable," and to consult your doctor about even the smallest of issues. These measures are important for preventing complications and staying healthy.