Does Graves’ Disease Affect Blood Sugar?

Does Graves’ Disease Affect Blood Sugar?

Short answer:
Yes. Graves’ disease and hyperthyroidism can disrupt blood sugar regulation, even if you don’t have diabetes.

If you have Graves’ disease, you may have noticed symptoms that feel like blood sugar issues – shakiness, anxiety, sudden hunger, or waking at odd hours feeling wired. You might wonder whether your thyroid condition is actually affecting your blood sugar.

The short answer is yes. Graves’ disease and hyperthyroidism can disrupt blood sugar regulation, even if you don’t have diabetes.

How Graves’ Disease Affects Blood Sugar

Excess thyroid hormone changes the way your body handles glucose in several important ways.

Your liver produces more glucose

The liver is the main driver of blood sugar disruption in hyperthyroidism. Thyroid hormones increase both gluconeogenesis (making new glucose) and glycogenolysis (releasing stored glucose). They also increase GLUT2 expression, which means more glucose gets released into your bloodstream (Eom YS et al., 2022).

Insulin becomes less effective

Hyperthyroidism creates a state of insulin resistance, primarily in the liver but also in muscle and fat tissue. Your body may produce more insulin to compensate, but that insulin doesn’t work as efficiently (Brenta G., 2011).

Insulin clearance increases

Thyroid hormones speed up insulin breakdown, so the insulin you produce doesn’t last as long in your system.

The net effect

More glucose entering your bloodstream combined with less effective insulin control equals greater blood sugar fluctuations – more spikes after meals and potentially more noticeable dips as levels drop.

Graves’ Disease And Blood Sugar: What the Research Shows

Studies using continuous glucose monitoring have found that people with uncontrolled Graves’ disease experience significantly greater blood sugar variability compared to healthy controls, even when standard glucose tests appear normal.

Specifically, researchers found:

• Higher mean amplitude of glycemic excursions (MAGE) – meaning bigger swings up and down
• Higher average blood glucose levels
• Delayed time to peak glucose after meals, particularly after breakfast
• FT4 levels were an independent predictor of variability– higher thyroid hormone meant more fluctuation

These effects occurred in people with normal glucose tolerance (Gao G et al., 2018).

Importantly, when thyroid levels were brought under control with treatment, glucose variability improved and insulin sensitivity normalised (Lakshmana Perumal N et al., 2019).

Can Graves’ Disease Cause Glucose Intolerance?

Yes. 

Research shows that around 40% of people with hyperthyroidism have some form of glucose intolerance- either impaired fasting glucose, impaired glucose tolerance, or in some cases, values in the diabetic range (Roubsanthisuk W et al., 2006).

The good news is that this often improves or resolves once thyroid levels are normalised with treatment.

The “Feels Like Low Blood Sugar” Problem

Many people with Graves’ disease report symptoms that mimic hypoglycaemia:

• Shakiness
• Anxiety
• Sweating
• Rapid heartbeat
• Sudden weakness
• Intense hunger

These symptoms overlap substantially with hyperthyroidism itself. 

Key point: In most cases, true hypoglycaemia (dangerously low blood sugar) is uncommon in Graves’ disease unless there are other factors involved, such as severe illness, liver dysfunction, or very poor nutritional intake.

What’s more likely is that your nervous system is sensitised, and you’re feeling blood sugar changes more intensely- even when levels aren’t technically low.

What This Means for You

If you have Graves’ disease, your body may be more reactive to blood sugar fluctuations. This doesn’t mean you have diabetes or a separate blood sugar disorder. It means your metabolic system is running faster and may benefit from strategies that promote stability.

Key implications:

• Standard tests may miss the variability. HbA1c can be misleading in hyperthyroidism because red blood cell turnover is altered. You may feel unstable even when labs look normal.
  
• Treatment helps. Nutrients like selenium have been studied as supportive approaches in Graves’ disease. Glucose control typically improves when thyroid levels are normalised. This is strong motivation to work with your medical team on getting your thyroid managed.
  
• Diet and lifestyle approaches studied in Graves’ disease show that while food won’t treat your thyroid, it can help reduce the amplitude of blood sugar swings and support more stable energy levels.
  

How to Support Stable Blood Sugar with Graves’ Disease

Because your system may be more sensitive to fluctuations, these practical strategies can help smooth out energy levels throughout the day.

Build balanced meals

Every meal should include:

• Protein – slows glucose absorption
• Healthy fats – prolongs energy release
• Fibre-rich carbohydrates – provides steady fuel

Examples: oats with yoghurt and seeds, eggs with wholegrain toast and avocado, lentils with vegetables and olive oil.

Don’t eat carbohydrates alone

Avoid “naked carbs” – fruit alone, toast alone, sugary snacks on their own. Always pair carbohydrates with protein or fat. Apple with peanut butter. Toast with eggs. Fruit with yoghurt.

This single habit dramatically reduces spike-and-drop patterns.

Eat regularly

Aim for meals every 3–4 hours. Long gaps can make energy dips feel worse when your metabolism is already running fast. Add small balanced snacks if needed.

Prioritise breakfast

The morning is already a high-stress-hormone window. Starting with a solid meal that includes protein, fat, and fibre helps prevent large morning swings.

Be strategic with caffeine

Avoid coffee on an empty stomach. Consider reducing intake if you feel anxious, shaky, or “wired then crashed.” Hyperthyroidism amplifies caffeine effects.

Consider an evening snack if you wake early

If you wake in the early hours feeling alert or wired, a small balanced snack before bed may help support overnight stability – yoghurt with nuts, oats with nut butter, or banana with almond butter.

Choose slower-release carbohydrates

Favour oats, quinoa, brown rice, wholegrain bread, and legumes over refined options. Slower carbs create a smoother glucose curve.

Manage stress

This is crucial. Stress hormones like cortisol and adrenaline directly increase blood glucose and can trigger that “wired” feeling. Yoga, walking, breathing exercises, and consistent sleep routines all help.

Stay hydrated

Dehydration can worsen fatigue and amplify “off” sensations.

What These Strategies Won’t Do

These approaches help stabilise energy and reduce the feeling of blood sugar swings. They don’t treat Graves’ disease itself. Your thyroid condition still needs appropriate medical management.

If your symptoms are severe, worsening, or persistent despite good self-care, review your thyroid treatment with your healthcare provider.

Key Takeaway

Graves’ disease can genuinely affect blood sugar regulation – increasing variability, reducing insulin effectiveness, and making you more sensitive to fluctuations. This happens even in people without diabetes, and it typically improves when thyroid levels are normalised.

While you work on getting your thyroid under control, supporting stable blood sugar through balanced meals, regular eating, and stress management can help reduce those “crash-like” feelings and support more consistent energy throughout the day.

FAQs: Graves’ Disease and Blood Sugar

References

Eom YS et al. (2022). Links between thyroid disorders and glucose homeostasis. Diabetes & Metabolism Journal. https://doi.org/10.4093/dmj.2022.0013

Brenta G. (2011). Why Can Insulin Resistance Be a Natural Consequence of Thyroid Dysfunction? Journal of Thyroid Research. https://doi.org/10.4061/2011/152850

Gao G et al. (2018). Glycemic variation in uncontrolled Graves’ disease patients with normal glucose metabolism: assessment by continuous glucose monitoring. Endocrine. https://doi.org/10.1007/s12020-018-1820-0

Lakshmana Perumal N et al. (2019). Insulin sensitivity and beta-cell function in Graves’ disease and their changes with the carbimazole-induced euthyroid state. European Thyroid Journal. https://doi.org/10.1159/000496924

Roubsanthisuk W et al. (2006). Hyperthyroidism induces glucose intolerance by lowering both insulin secretion and peripheral insulin sensitivity. Journal of the Medical Association of Thailand. PMID: 17718254