Italian Study Links Blood Sugar Spikes to Liver Fat in Type 1 Diabetes

A study from Italy has uncovered an important connection between blood sugar fluctuations and liver fat accumulation in adults living with Type 1 diabetes (T1D) — findings that carry significant implications for the millions of Americans managing this condition.

Researchers at the University of Verona and IRCCS Sacro Cuore-Don Calabria Hospital enrolled 262 adults with established Type 1 diabetes and used advanced liver imaging technology called vibration-controlled transient elastography (VCTE) to measure liver fat and stiffness. All participants also wore continuous glucose monitors (CGMs), giving researchers a detailed picture of day-to-day blood sugar patterns.

What the Researchers Found

The Italian team discovered that 35.1% of participants had metabolic dysfunction-associated steatotic liver disease (MASLD) — the new clinical term for what was previously called non-alcoholic fatty liver disease (NAFLD). An additional 4.6% showed signs of significant liver scarring (fibrosis). These rates are striking in a group with an average BMI of 25.8 kg/m² — considered only slightly above normal weight.

Crucially, the researchers identified that Time Above Range (TAR) — specifically the percentage of time blood glucose spent between 180–250 mg/dL — was independently associated with higher liver fat scores. This held true even after accounting for age, sex, BMI, HbA1c (average blood sugar control), and daily insulin dose.

To put this in perspective for CGM users: current American Diabetes Association (ADA) guidelines recommend keeping blood glucose below 180 mg/dL more than 70% of the time. The Italian study suggests that regularly exceeding this threshold — even moderately — may quietly contribute to fat buildup in the liver.

Why Glycemic Variability Matters Beyond HbA1c

One of the most valuable insights from this international research is that HbA1c alone doesn't tell the whole story. Two patients can have identical HbA1c values but very different patterns of highs and lows throughout the day. This Italian cohort demonstrates that those daily spikes into the 180–250 mg/dL range may be doing silent damage to the liver — damage that a standard quarterly blood test might miss entirely.

BMI remained the single strongest predictor of liver fat, followed by age and total daily insulin dose, but TAR was a statistically significant independent factor — meaning blood sugar spikes matter on their own, separate from body weight.

Why This Matters for US Patients

Liver disease is underdiagnosed in the American Type 1 diabetes population. Many patients and even clinicians focus primarily on kidney health, eye health, and heart health as diabetes complications — yet the liver is also vulnerable. This Italian research suggests that:

• CGM data can be a liver health tool. Your time-above-range percentage may signal more than just cardiovascular risk — it may reflect what's happening in your liver.
• You don't have to be overweight to have fatty liver disease. With a mean BMI of 25.8 kg/m², many participants in this study would not be flagged as high-risk by weight alone.
• Ask your doctor about liver screening. VCTE (FibroScan) is non-invasive and increasingly available in the US. Adults with T1D and any cardiometabolic risk factors may benefit from periodic screening.
• Reducing post-meal spikes matters. Working with your care team to minimize time in the 180–250 mg/dL range may support liver health, not just cardiovascular outcomes.

International Perspective: Why Italy?

Italy's nationalized healthcare system allows researchers to conduct rigorous multicenter studies with diverse patient populations and standardized diagnostic tools — providing a quality of real-world evidence that complements US clinical trials. The University of Verona has a particularly strong metabolic disease research program, lending this study additional credibility.

Source: Mantovani A, Ciardullo S, Sani E, et al. Association between continuous glucose monitoring metrics and metabolic dysfunction-associated steatotic liver disease in adults with type 1 diabetes undergoing vibration-controlled transient elastography: a multicenter cross-sectional study. Diabetes & Metabolism. 2025. DOI: 10.1016/j.diabet.2025.101684. PMID: 40623665.