From insulin sensitivity to kidney health: clinical studies are exploring the potential role of periodic fasting in managing type 2 diabetes.
World Diabetes Day, observed on November 14, is an opportunity to raise awareness not only about the prevention and management of diabetes, but also about new possibilities emerging from scientific research.
Among the nutritional approaches attracting growing interest is the Fasting-Mimicking Diet (FMD), a periodic dietary programme designed to reproduce some of the metabolic responses associated with fasting while still allowing the consumption of specific foods.
In recent years, several studies have explored the potential links between the fasting-mimicking diet, glucose metabolism, insulin sensitivity and metabolic complications associated with type 2 diabetes.
The findings are particularly interesting: some studies have reported improvements in specific metabolic markers and, in certain groups of participants, in parameters related to kidney function as well.
Type 2 diabetes: the role of insulin and glucose metabolism
Type 2 diabetes is a chronic metabolic condition characterised by impaired blood glucose regulation, meaning the concentration of glucose in the bloodstream.
One of the main mechanisms underlying the condition is insulin resistance. This occurs when the body's cells become less responsive to insulin, the hormone produced by the pancreas that allows glucose to enter cells and be used as an energy source.
To compensate for this reduced sensitivity, the pancreas may initially increase insulin production. Over time, however, pancreatic beta cells may gradually lose their ability to sustain this response, contributing to rising blood glucose levels.
Managing type 2 diabetes therefore requires a comprehensive approach, which may include a balanced diet, regular physical activity, weight management and, when necessary, medication.
In this context, researchers are also investigating nutritional strategies that may influence the metabolic processes involved in glucose regulation and insulin sensitivity.
The fasting-mimicking diet and diabetes: why periodic fasting is attracting scientific interest
Developed based on the research of Professor Valter Longo, director of the Longevity Institute at the University of Southern California, the fasting-mimicking diet is a five-day dietary programme characterised by controlled calorie intake and a specific nutritional composition.
Unlike complete fasting, it allows participants to consume selected plant-based foods while following a diet low in calories, protein and sugars, with a higher proportion of unsaturated fats and complex carbohydrates.
The goal is to promote some of the metabolic and cellular responses associated with fasting, including reductions in circulating glucose, insulin and IGF-1 (insulin-like growth factor 1), as well as changes in the way the body uses different energy sources.
These changes are particularly relevant to type 2 diabetes research, as insulin resistance and alterations in energy metabolism play a central role in the condition.
Periodic fasting may also help improve metabolic flexibility, which is the body's ability to adapt its use of different energy sources, switching between glucose and fatty acids depending on nutrient availability.
This is an area of research that Valter Longo and other scientists are also exploring, investigating the potential of periodic fasting strategies in managing metabolic conditions associated with ageing and excess body weight.
The 2022 study: the fasting-mimicking diet and kidney complications in type 2 diabetes
One of the most interesting studies exploring the relationship between periodic fasting and diabetes was published in 2022 in the Journal of Clinical Endocrinology & Metabolism, under the title Six-Month Periodic Fasting in Patients With Type 2 Diabetes and Diabetic Nephropathy: A Proof-of-Concept Study.
The study involved 40 people with type 2 diabetes and elevated albuminuria, a marker used to identify potential changes in kidney function. The presence of albumin in the urine can, in fact, be an early sign of diabetes-related kidney damage.
Participants were randomly assigned to two groups: the first followed a monthly fasting-mimicking diet protocol, while the second followed a Mediterranean-style diet. The intervention lasted six months, followed by a three-month follow-up period.
Researchers analysed several parameters, including the urinary albumin-to-creatinine ratio (ACR), a marker of insulin resistance and several biological markers associated with oxidative stress and cellular ageing.
The findings highlighted several important results:
- Insulin sensitivity: a reduction in the HOMA-IR index was observed in the group following the fasting-mimicking diet. This index is used to estimate insulin resistance.
- Albuminuria: among participants who had microalbuminuria at the beginning of the study, a reduction in the albumin-to-creatinine ratio was observed. This result was not found in participants with higher levels of albuminuria.
- Biological markers: researchers observed a reduction in suPAR levels, a biomarker associated with inflammatory processes and cellular senescence.
It is important to note that, when considering the entire study population, the change in albuminuria was not significantly different between the two groups. The positive findings related to kidney function therefore concern a specific subgroup of participants and cannot be generalised to everyone with diabetes.
Another interesting finding concerned how long the results lasted. At the end of the follow-up period, the reduction in HOMA-IR was still present, whereas the other improvements observed during the intervention had not been maintained to the same extent.
Overall, the study provided preliminary evidence of the potential role of periodic fasting in modulating insulin resistance and certain parameters associated with kidney complications in people with type 2 diabetes.
A further 2024 study: improved blood glucose control and reduced medication use
Another particularly important contribution came in 2024, with a randomised clinical trial published in the journal Diabetologia: Integration of a fasting-mimicking diet programme in primary care for type 2 diabetes reduces the need for medication and improves glycaemic control: a 12-month randomised controlled trial.
The study, which also involved Valter Longo, included 100 people with type 2 diabetes, aged between 18 and 75, with a body mass index (BMI) of 27 or higher.
Participants were divided into two groups: one followed a five-day-per-month fasting-mimicking diet programme alongside their usual medical care, while the other continued with standard care alone.
An important detail concerns the participants' treatment: they were taking metformin as their only glucose-lowering medication and/or following dietary interventions.
After 12 months, researchers observed several interesting results in the group following the fasting-mimicking diet:
- Reduction in glycated haemoglobin (HbA1c): the difference in HbA1c between the two groups was approximately 0.3 percentage points in favour of the fasting-mimicking diet. This is a particularly interesting finding, as it was achieved despite a reduction in glucose-lowering medication use, suggesting improved blood glucose control that was not attributable to greater reliance on medication.
- Reduced medication requirements: the score measuring glucose-lowering medication use decreased in the FMD group compared with the control group.
- Weight loss: there was an approximately 3.6 kg difference in body weight change between the two groups.
Another relevant finding concerned overall blood glucose management: 53% of participants following the fasting-mimicking diet showed improved glycaemic control, compared with 8% in the control group.
These results suggest that incorporating periodic fasting-mimicking diet cycles into standard medical care may help improve certain metabolic parameters in people with type 2 diabetes.
However, it is essential to point out that the study did not include people taking insulin or glucose-lowering medications other than metformin. The findings therefore cannot automatically be applied to everyone with diabetes.
New research perspectives: metabolic flexibility and kidney health
The relationship between the fasting-mimicking diet and diabetes was further explored in a study published in 2025 in the journal Molecular Metabolism. Some of the researchers involved in the 2022 study, including Valter Longo, also contributed to this research.
The study, entitled Periodic fasting induced reconstitution of metabolic flexibility improves albuminuria in patients with type 2 diabetes, took a closer look at the metabolic changes associated with periodic fasting in participants with type 2 diabetes and diabetic nephropathy.
This was a subsequent analysis of data from the previous clinical trial, rather than a new independent clinical study.
Researchers observed that, among participants who experienced improvements in albuminuria, periodic fasting was associated with persistent metabolic changes, including greater use of fatty acids as an energy source and better coordination of the processes involved in lipid metabolism.
These findings led researchers to suggest that restoring metabolic flexibility may be one of the mechanisms involved in the improvements observed in some patients.
The research therefore suggests that the effects of periodic fasting may go beyond simply reducing calorie intake, involving more complex metabolic processes.
Of course, these findings need to be confirmed through larger and more extensive clinical studies.
The fasting-mimicking diet and diabetes: what do we know so far?
Available scientific evidence is helping build an increasingly interesting picture of the relationship between the fasting-mimicking diet and glucose metabolism.
The 2022 and 2025 studies focused primarily on the potential links between periodic fasting, insulin resistance, metabolic flexibility and certain indicators of kidney health.
The 2024 clinical trial, meanwhile, provided findings on blood glucose control and medication use in people with type 2 diabetes receiving primary care.
Overall, these studies suggest that periodic fasting may represent a complementary nutritional approach worth further investigation as part of metabolic health management.
However, it is important to remember that diabetes is a complex condition and dietary strategies should always be tailored to individual needs.
In particular, people taking medications that can cause hypoglycaemia need to be especially careful with calorie-restricted protocols. Any decision to introduce the fasting-mimicking diet should be assessed and supervised by a treating physician or diabetes specialist, who can evaluate individual circumstances and manage any necessary adjustments to medication.
The fasting-mimicking diet does not replace medication, blood glucose monitoring or the advice of a healthcare professional.
Research into the relationship between periodic fasting and diabetes is still evolving, but the findings available so far are opening up new perspectives on how specific nutritional interventions may influence metabolism and long-term health.
