This provides direct experimental support for the Type 3 Diabetes hypothesis, reinforcing the idea that Alzheimer’s disease is a brain-specific form of insulin resistance. The study showed that when insulin signaling is disrupted in the brain, neurons become starved for energy, oxidative stress increases, and key pathological features of AD—including tau tangles and amyloid plaques—begin to develop.

Alzheimer’s disease (AD) is increasingly associated with metabolic dysfunction, particularly insulin resistance, which impairs neuronal signaling and energy metabolism. Disruption of brain insulin pathways contributes to amyloid-beta accumulation, tau pathology, and neuroinflammation.

To address this question, we utilized an established experimental model of chronic high-fat diet (HFD) feeding of C57BL/6 mice to examine the degree to which obesity/T2DM was sufficient to produce histopathological, molecular, and/or biochemical brain abnormalities of AD-type neurodegeneration, i.e., T3DM. High-fat diet feeding for 16 weeks doubled mean body weight, caused T2DM, and marginally reduced mean brain weight.80 Those effects were associated with significantly increased levels of tau, IGF-1 receptor, IRS-1, IRS-4, ubiquitin, glial fibrillary acidic protein (GFAP), and 4-hydroxynonenal and decreased expression of β actin. Importantly, HFD feeding also caused brain insulin resistance manifested by reduced top-level (Bmax) insulin receptor binding and modestly increased brain insulin gene expression.

November 7, 2024 - In recent years, there has been growing interest within the scientific community regarding the possible connection between AD and type T2DM, leading some researchers to propose the conceptual term “type 3 diabetes” as a way to describe this link. This term is intended to underscore the potential role of insulin resistance in the brain and its association with neurodegenerative processes in AD.

November 5, 2025 - Type 3 diabetes (T3D) is characterized by chronic insulin resistance and insulin deficiency in the brain, leading to neuronal death, inflammation, oxidative stress, apoptosis, and synaptic dysfunction.

April 20, 2022 - In particular, glucose metabolism impairment has demonstrated to be a key regulatory element in the onset and progression of AD, which is why nowadays AD is considered the type 3 diabetes.

February 18, 2025 - Increasing evidence suggests that Aβ toxicity, tau hyperphosphorylation, oxidative stress, and neuroinflammation are attributed to CNS insulin resistance, thereby contributing to neurodegeneration (Takeda et al. 2012; Wei et al. 2021; Leclerc et al. 2022). Considering the shared molecular and cellular features between type 1 diabetes, type 2 diabetes mellitus (T2DM), and insulin resistance in older adults, which are associated with memory impairment and cognitive decline, researchers have coined the term “Type 3 Diabetes mellitus (T3DM)” to emphasize the critical role of insulin in brain energy supply (Steen et al.

April 20, 2022 - In particular, glucose metabolism impairment has demonstrated to be a key regulatory element in the onset and progression of AD, which is why nowadays AD is considered the type 3 diabetes.

August 27, 2025 - Alzheimer’s disease (AD) is increasingly associated with metabolic dysfunction, particularly insulin resistance, which impairs neuronal signaling and energy metabolism. Disruption of brain insulin pathways contributes to amyloid-beta accumulation, ...

T1D is mainly observed in children and young adults, while T2DM is more common among adults and is responsible for 90% of the incidences globally [6]. Some epidemiological studies suggest that insulin resistance increases the risk for dementia and AD, even in nondiabetic populations.

April 30, 2020 - Overall, the consequences of impaired insulin signaling are attributed to impaired metabolism in the brain that may lead to brain malfunction, providing possible explanations for the connection between diabetes, obesity, and AD [11], as shown in Table 1. Table 1. Causal model for the potential associated with between T3D and AD. Insulin resistance or dysfunction of insulin signaling is a universal feature of T2D, due to altered glucose metabolism and its interdependence on cell death pathways form the basis of linking T3D with AD, as shown in Figure 3.

October 18, 2023 - Alzheimer Associated Diabetes Mellitus, commonly known as Type 3 Diabetes Mellitus (T3DM) is a distinct subtype of diabetes with a pronounced association with Alzheimer's disease (AD).

October 25, 2017 - This form of diabetes is associated with Alzheimer's disease. Type 3 diabetes occurs when neurons in the brain become unable to respond to insulin, which is essential for basic tasks, including memory and learning.

June 30, 2024 - Unfortunately, no particular medications exist to treat AD, as the current treatments only impede its progression.The link between AD and type 2 diabetes (T2D) has been increasingly revealed by research; the danger of developing both AD and T2D rises exponentially with age, with T2D being especially prone to AD. This has propelled researchers to investigate the mechanism(s) underlying this connection. A critical review of the relationship between insulin resistance, Aβ, oxidative stress, mitochondrial hypothesis, abnormal phosphorylation of Tau protein, inflammatory response, high blood glucose levels, neurotransmitters and signaling pathways, vascular issues in AD and diabetes, and the similarities between the two diseases, is presented in this review.

In 2008, de la Monte and Wands’ ... mellitus. In a pivotal study, Craft revealed that IR increases AD risk by elevating Aβ42 and inflammatory cytokines in the brain.53 De Felice et al....

Currently, there is a rapid growth in the literature pointing toward insulin deficiency and insulin resistance as mediators of AD-type neurodegeneration, but this surge of new information is riddled with conflicting and unresolved concepts regarding the potential contributions of type 2 diabetes mellitus (T2DM), metabolic syndrome, and obesity to AD pathogenesis. Herein, we review the evidence that (1) T2DM causes brain insulin resistance, oxidative stress, and cognitive impairment, but its aggregate effects fall far short of mimicking AD; (2) extensive disturbances in brain insulin and insuli

May 20, 2010 - Overview: There appear to be many ... utilization and energy metabolism.6,19 As T2DM is associated with peripheral insulin resistance, AD is associated with brain insulin resistance.20 Early in AD, there seems to be inadequate ...

August 15, 2019 - For this reason, some researchers have even referred to AD as Type 3 Diabetes (T3D; de la Monte, 2012, 2014; Chami et al., 2016; Kandimalla et al., 2017; Kang et al., 2017; Tong et al., 2017). This concept describes a brain-specific pathological situation in which insulin and IGF resistance is developed inducing cognitive impairments and neurodegeneration...

May 12, 2025 - In recent years, researchers have ... This concept suggests that Alzheimer's may be, at least in part, a metabolic disorder affecting the brain, much like diabetes affects the body....

February 28, 2022 - Oligomers are toxic to nerve cells, while misfolded oligomers can transmit the wrong folding to their neighbors acting as prions [44,45,46,47]. The aggregation of the amyloid peptide into oligomers or fibrils, in turn, is involved in the progression of AD [48]. Reduced levels of IGF-1(insulin-like growth factor) [49] and insulin resistance may result in reduced IGF-1 and insulin brain uptake, causing β-amyloid accumulation. Consequently, increased β-amyloid levels antagonize insulin and IGF-1 receptor binding, which results in the secretion of inflammatory agents and the onset of insulin resistance [50]. Moreover, these factors of insulin dysfunction and inflammation, in combination with oxidative stress, enhance the toxicity and concentration of β-amyloid [51] in a pathological feedback cycle.