Epilepsy and diabetes share more biological terrain than most people realize. People with type 1 diabetes face roughly three times the risk of developing epilepsy compared with the general population, and the connections run in both directions: blood sugar swings can directly provoke seizures, shared autoimmune processes can drive both conditions, and the medications used to treat one disease can worsen or improve the other. Understanding these links matters for the millions of people managing either condition, and increasingly, researchers are finding that drugs designed for diabetes may hold genuine promise as seizure treatments.
How Blood Sugar Extremes Trigger Seizures
The most immediate connection between diabetes and seizures is straightforward: the brain depends on a steady supply of glucose, and when blood sugar drops too low or climbs too high, neurons can misfire. These are not epilepsy in the traditional sense. They are acute symptomatic seizures, provoked by a metabolic crisis rather than by an underlying seizure disorder. But for someone living with diabetes, the distinction matters less than the experience itself.
Severe hypoglycemia is the more dangerous trigger. When glucose falls sharply, the hippocampus is especially vulnerable. Lab studies show that dropping glucose to very low concentrations produces seizure-like electrical activity in the vast majority of brain slices tested, with the events originating in the CA3 region of the hippocampus and spreading outward.1PubMed. Hypoglycemia-induced alterations in hippocampal intrinsic rhythms: Decreased inhibition, increased excitation, seizures and spreading depression Part of the problem is that as glucose drops, the brain’s main inhibitory signaling weakens while excitatory firing ramps up. These hypoglycemic seizures cause lasting damage: they are followed by a dramatic and often irreversible loss of synaptic transmission in the hippocampus.2PubMed. Hypoglycemic seizures during transient hypoglycemia exacerbate hippocampal dysfunction Early research also suggests that insulin itself may play a role beyond simply lowering glucose, by altering the transport of sodium and potassium into the brain and raising brain osmolality, which can independently push neurons toward seizure activity.3The Journal of Clinical Investigation. Mechanisms of Seizures and Coma in Hypoglycemia
Hyperglycemia can also cause seizures, though the pattern looks different. In nonketotic hyperglycemia, where blood sugar is extremely high but ketones are not present, seizures tend to be focal rather than generalized. A case report described a young woman who developed focal faciobrachial seizures as a rare complication of nonketotic hyperglycemia, and her seizures only resolved once anti-seizure medications were added to insulin therapy.4PubMed Central. A Case Report of Nonketotic Hyperglycemic Seizures: A Diagnostic Dilemma This contrast between generalized seizures in hypoglycemia and focal seizures in hyperglycemia is a clinically useful pattern. It can help guide emergency treatment when a patient with diabetes presents with a seizure and the glucose level points toward one extreme or the other.
The Autoimmune Thread Connecting Type 1 Diabetes and Epilepsy
Beyond acute blood sugar episodes, type 1 diabetes and epilepsy share a deeper biological overlap rooted in the immune system. A population-based study found that people with type 1 diabetes had an epilepsy incidence rate of about 132 per 100,000 person-years, compared with 44 per 100,000 in matched controls, translating to a threefold increase in risk even after adjusting for other factors.5PubMed Central. Type 1 diabetes mellitus and risk of incident epilepsy: a population-based, open-cohort study That elevated risk persisted whether the analysis included or excluded people whose type 1 diabetes began in adulthood, suggesting the link is not just about childhood vulnerability.
The molecule at the center of this overlap is glutamic acid decarboxylase, specifically its 65-kilodalton form, GAD65. This enzyme converts glutamate into GABA, the brain’s primary inhibitory neurotransmitter. Autoantibodies against GAD65 appear at low levels in many people with type 1 diabetes, where they serve as diagnostic markers. But at high levels, those same antibodies show up in neurological conditions including refractory epilepsy, autoimmune encephalitis, and stiff person syndrome.6PubMed Central. Co-occurrence of Anti-GAD65 Syndrome, Type 1 Diabetes Mellitus, and Focal Seizures With Impaired Awareness When high-titer anti-GAD65 antibodies attack GAD65 in the brain, less GABA gets produced, and inhibition drops. The result can be seizures that resist standard medications.
Not every person with both type 1 diabetes and epilepsy has autoimmune epilepsy, though. Research examining GAD65 antibody patterns in people diagnosed with both conditions found two distinct groups. In one group, type 1 diabetes co-occurred with non-autoimmune epilepsy, meaning the two conditions were present together but were driven by separate causes. In the other group, the GAD65 antibodies themselves were part of the epileptic process.7PubMed Central. GAD65 autoantibody characteristics in patients with co-occurring type 1 diabetes and epilepsy may help identify underlying epilepsy etiologies Telling these two scenarios apart matters for treatment: if the epilepsy has an autoimmune basis, immunotherapy may help where conventional anti-seizure drugs fail. A case involving a child diagnosed with type 1 diabetes before age one who developed drug-resistant epilepsy at about two and a half years old showed that high GAD65 antibody titers were present in both blood and cerebrospinal fluid, and the antibodies had binding characteristics more similar to those seen in stiff person syndrome than in typical diabetes.8PubMed Central. Epilepsy and behavioral changes, type 1 diabetes mellitus and a high titer of glutamic acid decarboxylase antibodies
How Insulin Resistance Affects the Brain
The autoimmune story centers on type 1 diabetes, but type 2 diabetes has its own pathway into seizure susceptibility: insulin resistance. The brain is not just a passive recipient of glucose from the bloodstream. It has insulin receptors, and those receptors participate in maintaining the balance between excitatory and inhibitory signaling, protecting neurons from oxidative stress, and supporting mitochondrial function. When insulin signaling in the brain goes awry, that balance can tip toward excitability.
Insulin resistance in the brain disrupts synaptic transmission, impairs the generation of new mitochondria, and throws off the balance of oxidizing and protective molecules within neurons, creating a feedback loop that connects metabolic stress to epileptic activity.9PubMed Central. The Hidden Metabolic Roots of Epilepsy One review of insulin signaling pathways in epilepsy describes how disruption of these pathways can lead to impaired glucose use by neurons, lower GABA levels, and increased neuronal excitability, all of which raise seizure susceptibility.10American Journal of Biopharmacy and Pharmaceutical Sciences. Insulin pathways in epilepsy: Link between metabolism and brain activity
Diabetes also compromises the blood-brain barrier. Changes in plasma glucose, whether too high or too low, have been linked to disruption of the tight junctions that keep the barrier intact, altered transport of glucose and other essential molecules across it, and increased oxidative stress in the tiny blood vessels that supply the brain.11PubMed Central. Diabetes Mellitus and Blood-Brain Barrier Dysfunction: An Overview A leakier blood-brain barrier can expose the brain to inflammatory molecules and toxins that normally stay in the bloodstream, further lowering the threshold for seizures.
When Hypoglycemia Looks Like Epilepsy
One of the more treacherous clinical overlaps between diabetes and epilepsy is diagnostic confusion. Nocturnal hypoglycemia in people with diabetes can produce episodes of involuntary movement, unresponsiveness, and bizarre behavior that closely mimic seizures or sleepwalking. In one reported case, a 79-year-old woman with type 2 diabetes was admitted for evaluation of nightly episodes in which she shook her legs, fumbled with bedclothes, crawled around the room with her eyes closed, and could not be reached by verbal communication. Her EEG during an episode showed diffuse slow-wave activity with no epileptic discharges, and her blood glucose measured just 35 mg/dL. Both the EEG abnormalities and the clinical symptoms resolved promptly after intravenous glucose.12PubMed Central. Abnormal Nocturnal Behavior due to Hypoglycemia in a Patient with Type 2 Diabetes
These episodes can easily be misdiagnosed as nighttime epilepsy, REM sleep behavior disorder, or sleepwalking. One case report describes a patient initially worked up for nocturnal epilepsy before the actual cause, hypoglycemia, was identified through polysomnography combined with extended EEG monitoring and concurrent glucose measurement.13PubMed Central. Abnormal nocturnal behavior due to hypoglycemia: A case report For anyone with diabetes who has unexplained nighttime episodes, the practical takeaway is that continuous glucose monitoring or at least a blood sugar check during or immediately after an event can prevent months of unnecessary neurological workups and inappropriate anti-seizure medication.
Anti-Seizure Medications That Worsen Metabolic Health
The treatment side of the epilepsy-diabetes relationship introduces another set of complications. Valproate, one of the most widely prescribed anti-seizure drugs, can push people toward insulin resistance and weight gain. A prospective study comparing valproate with levetiracetam found that after six months, people on valproate had significantly higher insulin levels, and roughly one in seven developed insulin resistance. Valproate also drove increased body weight and unfavorable changes in appetite-regulating hormones. Levetiracetam, by contrast, produced none of these metabolic changes.14PubMed. Is there any concern of insulin resistance and metabolic dysfunctions with antiseizure medications? A prospective comparative study of valproate vs. levetiracetam
An earlier study focusing on girls treated with valproate for epilepsy found that those who gained weight after starting the drug had insulin levels nearly twice as high as those who did not gain weight, and the weight-gaining group showed clear insulin resistance.15PubMed. Insulin resistance in epileptic girls who gain weight after therapy with valproic acid For someone who already has prediabetes or risk factors for type 2 diabetes, starting valproate could accelerate the path toward full-blown diabetes. This is worth discussing with a neurologist, especially since alternative anti-seizure medications exist that do not carry the same metabolic baggage.
Diabetes Drugs With Anti-Seizure Potential
Perhaps the most intriguing area of overlap between these two conditions is the growing evidence that certain diabetes medications may actively protect against seizures. Metformin, the most commonly prescribed drug for type 2 diabetes worldwide, has shown anti-seizure effects in animal studies through several mechanisms: it activates a cellular energy sensor called AMPK, inhibits a growth-signaling pathway called mTOR that is overactive in some forms of epilepsy, and boosts a protective brain protein called BDNF.16PubMed Central. New insights on the potential anti-epileptic effect of metformin: Mechanistic pathway In animal models of temporal lobe epilepsy, metformin at higher doses significantly slowed seizure progression and protected hippocampal neurons from dying.17Journal of Alzheimers & Neurodegenerative Diseases. Dose-Dependent Anticonvulsant and Protective Effects of Metformin in Kainate Induced Temporal Lobe Epilepsy Animal studies have also suggested that metformin can improve the cognitive problems, such as learning and memory deficits, that often accompany epilepsy.18PubMed. Envisioning the neuroprotective effect of Metformin in experimental epilepsy: A portrait of molecular crosstalk
The evidence is stronger, and more clinically relevant, for GLP-1 receptor agonists. These drugs, originally developed for type 2 diabetes and now widely used for weight management, have attracted attention for effects that extend well beyond blood sugar control. A large observational analysis found that GLP-1 receptor agonist use was linked to a significantly lower risk of epilepsy, with a hazard ratio of 0.84, and the protective association was evident at one, three, and five years of use.19PubMed Central. The Effect of GLP-1 Receptor Agonists on Epilepsy: No Appetite for Seizures In adults who already had epilepsy, starting a GLP-1 receptor agonist was associated with lower risk of seizure recurrence, lower hospitalization rates, and substantially lower all-cause mortality.20PubMed. Seizure recurrence after GLP-1 receptor agonist initiation in adults with epilepsy A scoping review of both preclinical and human data found that GLP-1 receptor agonists consistently show antiseizure and neuroprotective effects, likely through reduction of neuroinflammation, oxidative stress, and promotion of neuronal survival, with risk reductions across studies ranging from about 10% to 57%.21PubMed. GLP-1 receptor agonists in people with epilepsy: A scoping review of clinical data, safety, and therapeutic implications
These are observational findings, not results from randomized trials, so there are limits to how far the conclusions can go. People taking GLP-1 receptor agonists may differ from those who don’t in ways that independently affect seizure risk. Still, the consistency of the signal across multiple studies and endpoints has been enough to generate serious interest in prospective trials.
Drug Interactions Between Epilepsy and Diabetes Treatments
For people managing both conditions, drug interactions deserve attention. Topiramate, an anti-seizure medication also used for migraine prevention, interacts with both metformin and pioglitazone. Taking topiramate alongside metformin modestly increases metformin levels in the body while slightly decreasing topiramate levels. In practice, the interaction is not dramatic enough to require dose changes for most people, but it is worth monitoring. More concerning is the combination with pioglitazone: topiramate reduces the blood levels of pioglitazone and its active breakdown products, with one metabolite’s exposure dropping by about 60%. That reduction could undermine blood sugar control, particularly in women, where the effect appeared more pronounced.22PubMed. Pharmacokinetic interactions between topiramate and pioglitazone and metformin Anyone on pioglitazone who starts topiramate should have their blood sugar tracked more closely, since the diabetes drug may not be doing as much work as expected.
Maternal Diabetes and Seizures in Newborns
The diabetes-epilepsy link extends to pregnancy. A nested case-control study found that pre-existing diabetes in mothers (type 1 or type 2 diagnosed before pregnancy) was associated with about a 50% increased risk of seizures in their newborns, even after adjusting for confounding factors. Gestational diabetes, however, did not carry the same risk.23PubMed Central. The association between maternal diabetes and neonatal seizures: a nested case–control study The likely mechanism involves the effect of maternal blood sugar instability on the developing fetal brain, particularly during the last trimester when the brain is growing most rapidly. Neonatal seizures, while often self-limiting, can signal underlying brain injury, so the finding underscores the importance of tight glycemic control in pregnant women with pre-existing diabetes.
Children With Type 1 Diabetes and Brain Health
Parents of children with type 1 diabetes often worry about the long-term effects of the disease and its treatment on their child’s brain. A meta-analysis of cognitive function in children with type 1 diabetes found that the overall cognitive impact of seizures related to severe hypoglycemia was surprisingly small, with a negligible average effect across studies. Children with early-onset diabetes (diagnosed at a young age) did show larger deficits in learning and memory compared with non-diabetic children, but these deficits appeared more closely tied to the disease itself and its management than to individual seizure episodes.24PubMed Central. Cognitive function in children with type 1 diabetes: a meta-analysis The practical message is that preventing severe hypoglycemia remains important for many reasons, but a single seizure related to low blood sugar is unlikely to cause lasting cognitive damage on its own. Chronic blood sugar management matters more than any single event.
The Ketogenic Diet as Shared Territory
The ketogenic diet sits at a fascinating intersection of epilepsy and diabetes management. In epilepsy, it has been used since the 1920s to reduce seizures, especially in children whose seizures resist medications. It works by shifting the brain’s fuel source from glucose to ketone bodies, which alters neurotransmitter balance and energy metabolism in ways that raise the seizure threshold.25PubMed. Control of seizures by ketogenic diet-induced modulation of metabolic pathways In the diabetes world, very low-carbohydrate diets have gained popularity for their ability to lower blood sugar and reduce insulin requirements. For someone with both conditions, the ketogenic diet might seem like a natural fit, but it requires careful medical supervision. Dramatically cutting carbohydrates while on insulin or certain diabetes medications raises the risk of dangerous hypoglycemia, and the high fat content of a strict ketogenic diet can worsen cardiovascular risk factors that are already elevated in people with diabetes. The diet also requires close monitoring of ketone levels, since diabetic ketoacidosis, a life-threatening complication, can be triggered or masked by an intentionally ketotic state. This is one area where managing both conditions simultaneously requires genuine coordination between a neurologist and an endocrinologist rather than independent treatment plans.