MS patients show greater resistance to insulin effects, analysis finds
Higher levels of blood sugar-regulating hormone also found in patients
Multiple sclerosis (MS) patients exhibited greater resistance to the effects of insulin — the hormone responsible for keeping the body’s blood sugar levels within a healthy range — and had higher overall insulin levels compared with people without the neurodegenerative disease, a meta-analysis of published studies found.
These findings lend support to growing evidence that metabolic disturbances such as insulin resistance can influence brain function and contribute to neurological conditions, according to the researchers.
“The meta-analysis revealed a significant link between [insulin resistance] and MS, as well as between insulin levels and MS,” the team wrote. “Emphasizing the causal relationship between insulin alterations and MS could provide insights for developing effective disease control methods in the future.”
The study, “Association between insulin resistance and multiple sclerosis: a systematic review and meta-analysis,” was published in Metabolic Brain Disease.
Investigating the effects of insulin resistance in MS
The exact causes of MS are not fully known, but the disease is believed to arise from a combination of genetic, environmental, and lifestyle-related risk factors, some of which might also influence its severity and course.
Specifically, certain metabolic perturbations, or disturbances, particularly those related to blood sugar control and insulin dynamics, might contribute to MS, researchers note.
Insulin resistance happens when the body does not respond as it should to insulin. Typically, this hormone moves blood sugar, or glucose, out of the bloodstream to be used as a cellular energy source, causing blood sugar levels to rise. This is a key feature of type 2 diabetes.
The brain is sensitive to the effects of insulin, which regulates cognition, feeding behaviors, and other neurological functions. Moreover, insulin can directly affect inflammation, which is a core feature of MS.
Insulin resistance or other altered insulin dynamics could thus be involved in the neurodegenerative disease. Indeed, some reports have suggested that insulin resistance and other metabolic disturbances are common in MS, but their exact roles are not fully understood.
More work needed to understand the nature of the relationship
Now, a team of researchers from Iran conducted a systematic review and meta-analysis to learn more about the possible link between insulin and MS. A meta-analysis is a way of collectively analyzing data from multiple separate studies. Overall, the analysis included 18 studies published between 2012 and 2022.
The results showed that the degree of insulin resistance was significantly higher in MS patients relative to control participants without MS. However, there was high variability between the different studies.
Circulating levels of insulin in the bloodstream also were significantly higher in MS patients, a factor known to contribute to insulin resistance over time.
Relationships between insulin resistance and MS were stronger when looking at studies that recruited patients with both relapsing and progressive forms of MS compared with those that only involved people with relapsing-remitting MS.
The researchers speculate that this could be related to stronger immune dysregulation in progressive MS patients, leading to more significant insulin disruptions.
Taken together, the findings suggest a possible role for insulin resistance in MS. Still, more high-quality studies involving larger groups of patients are “essential to validate these associations,” the researchers wrote.
Moreover, more work is needed to probe the exact nature of the relationship.
Some studies suggest that insulin resistance is a harmful consequence of strong inflammation in the disease, while others have proposed that these altered insulin responses are a compensatory strategy the body uses to offer more energy to the brain in the disease state.
It also remains to be seen exactly how insulin resistance might in turn influence immune and nervous system function in MS patients, the team concluded.
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