Why the Same Heart Test Results Can Mean Different Things in Type 1 and Type 2 Diabetes

Global longitudinal strain, or GLS, is a heart imaging technique that measures how well the heart muscle contracts and relaxes. It can reveal subtle changes in heart function that standard tests might miss—changes that happen before someone develops obvious symptoms or signs of heart problems.

Both people with Type 1 and Type 2 diabetes are at increased risk for heart disease, so doctors are increasingly using GLS to catch early warning signs. The challenge is that a similar GLS result in someone with Type 1 diabetes and someone with Type 2 diabetes might not mean the same thing biologically.

In Type 1 diabetes, the heart problems that show up on GLS testing appear to stem primarily from the metabolic stress of chronic high blood sugar. Persistent hyperglycemia triggers oxidative stress—a cellular imbalance that damages heart tissue. At the same time, chronic high blood sugar can reduce blood flow to the smallest blood vessels that feed the heart muscle.

Over time, these factors lead to remodeling of the heart tissue itself, with changes in its structure that impair how it contracts. This constellation of problems—high blood sugar damage, reduced blood flow, and structural remodeling—creates a distinct pattern of heart dysfunction in Type 1 diabetes.

Type 2 diabetes follows a different biological pathway. Insulin resistance, obesity, and excess fat in the bloodstream appear to be more central drivers of heart dysfunction in this group. These factors interfere with how heart cells produce and use energy, disrupting the mitochondria—the cell's power plants.

While Type 2 diabetes shares some overlapping mechanisms with Type 1, the emphasis is different. The heart problems that emerge tend to be shaped more by metabolic factors tied to insulin resistance and energy metabolism than by the direct damage from chronically elevated blood sugar alone.

Because similar GLS results can reflect different underlying problems, interpreting the test requires more than just looking at a single number. Doctors should consider your diabetes type, how long you've had diabetes, your average blood sugar control over time, other health conditions, and findings from other heart imaging tests.

GLS is sensitive—meaning it can catch changes—but it is not specific to any one cause. The same abnormal result could reflect high blood sugar damage in one person, energy metabolism problems in another, or a combination of factors. A mechanistically informed approach—one that accounts for these different biological pathways—may help doctors better understand your individual risk and make more tailored decisions about monitoring and treatment.

While GLS testing is a valuable tool for detecting early heart changes in diabetes, the results must be interpreted thoughtfully and in the full context of your health. Type 1 and Type 2 diabetes represent different diseases with different mechanisms, and that difference extends to how the heart is affected. Understanding these distinctions supports more precise, personalized approaches to heart health monitoring in diabetes.

Source: Echocardiography (Mount Kisco, N.Y.). Evidence type: PubMed indexed literature. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.