If you have diabetes and keep feeling tired, losing hair, or gaining weight despite eating less, it might not just be your blood sugar. You could also have a thyroid problem-and you’re not alone. About 30% of people with diabetes also have thyroid disease. That’s more than 1 in 3. And when both conditions show up together, symptoms get messy. Fatigue? Could be low blood sugar. Or it could be an underactive thyroid. Weight gain? Maybe insulin resistance. Or maybe your thyroid isn’t making enough hormone. The lines blur, and that’s dangerous.
Why Diabetes and Thyroid Disease Show Up Together
These two conditions don’t just happen by chance. They’re linked by the same root cause: autoimmunity. In Type 1 diabetes, the immune system attacks the pancreas. In Hashimoto’s or Graves’ disease, it attacks the thyroid. Same faulty trigger. People with Type 1 diabetes are 5 to 10 times more likely to develop thyroid disease than someone without diabetes. Even in Type 2 diabetes, the risk is higher than average. Thyroid hormones directly affect how your body uses insulin and glucose. When your thyroid is underactive (hypothyroidism), your metabolism slows down by 25-30%. That means glucose sticks around longer in your blood, raising your sugar levels and making insulin less effective. On the flip side, an overactive thyroid (hyperthyroidism) speeds up your metabolism by 15-20%. Glucose gets burned off too fast, causing unpredictable drops in blood sugar-even if you’re eating normally. And it goes both ways. Diabetes messes with your thyroid too. High blood sugar damages nerves and blood vessels, including those that help convert T4 (the inactive thyroid hormone) into T3 (the active one). That’s why some diabetic patients end up with normal TSH levels but still feel hypothyroid. Their body just can’t use the hormone properly.Symptoms That Look the Same-But Aren’t
Here’s where things get tricky. Both conditions cause:- Unexplained weight changes (up to 70% of people with both have this)
- Extreme fatigue (78% report this)
- Hair thinning or loss (42%)
- Dry, itchy skin (37%)
- Mood swings and depression (55% and 29%, respectively)
- Feeling too hot or too cold (61%)
- Muscle cramps that don’t go away with stretching (33%)
- A hoarse voice you can’t explain (19%)
- Memory lapses or brain fog that’s worse than usual (45%)
What Your Doctor Should Be Checking
If you have diabetes, you need thyroid screening. Not someday. Now. The American Diabetes Association recommends:- Annual TSH blood test for everyone with Type 1 diabetes
- Annual TSH test for Type 2 diabetes patients with risk factors: family history of thyroid disease, female gender, age over 60, or presence of other autoimmune conditions
- Thyroid antibody testing (TPOAb and TgAb) at diagnosis-especially if you have Type 1
How to Manage Both at the Same Time
Treating one without the other is like fixing one tire while the other’s flat. You’ll keep going in circles.- Thyroid medication timing matters. Levothyroxine should be taken on an empty stomach, 30-60 minutes before food. But if you have diabetic gastroparesis (delayed stomach emptying), absorption drops by 15-20%. Talk to your doctor about splitting your dose or switching to a different formulation.
- Insulin needs change with thyroid status. If your thyroid is underactive, you may need 15-25% less insulin. If it’s overactive, you may need 20-40% more. Always adjust under medical supervision.
- Use continuous glucose monitoring (CGM). A 2022 JAMA study showed CGM users with both conditions had 32% fewer hypoglycemic events and better time-in-range. You’ll catch hidden lows and see how thyroid changes affect your sugar.
- Check thyroid levels every 3 months if you have both conditions-not once a year. Your needs shift fast.
Lifestyle Changes That Help Both
You can’t out-exercise or out-diet your hormones-but you can support them. A Mediterranean diet (rich in olive oil, fish, nuts, vegetables, and whole grains) has been shown in clinical trials to:- Lower HbA1c by 0.8-1.2%
- Improve TSH levels by 0.5-0.7 mIU/L
- Reduce LDL cholesterol by 15-20% (critical since both conditions raise heart disease risk)
The Hidden Cost of Ignoring the Link
People with both diabetes and thyroid disease pay more-in money and health.- Annual healthcare costs are $4,872 higher than for diabetes alone.
- They’re 37.2% more likely to develop diabetic retinopathy.
- Cholesterol and triglycerides spike: LDL up by 18-22 mg/dL, triglycerides up by 25-30 mg/dL.
- Emergency visits and hospitalizations are 17-22% more frequent if thyroid issues go untreated.
What’s New in 2025
The field is changing fast. In early 2025, results from the NIH-funded TRIAD study showed that early treatment of subclinical hypothyroidism in prediabetic patients reduced progression to full Type 2 diabetes by 41% over 18 months. Also, GLP-1 receptor agonists (like semaglutide), which are used for diabetes and weight loss, were found in a 2024 pilot study to improve thyroid function in 63% of patients with subclinical hypothyroidism. That’s not a cure-but it’s a promising side benefit. New guidelines from the American Association of Clinical Endocrinologists, released in October 2024, now include specific algorithms for managing thyroid dysfunction in Type 1 vs. Type 2 diabetes. For the first time, there’s a clear roadmap: what to test, when to adjust meds, and how to avoid dangerous interactions.What to Do Right Now
If you have diabetes:- Check your last TSH result. If it’s been over a year, schedule a test today.
- Write down every symptom-even the small ones. Fatigue? Hair loss? Cold hands? Brain fog? Bring the list to your doctor.
- Ask for TSH, free T4, free T3, and thyroid antibodies (TPOAb, TgAb).
- If you’re on insulin or GLP-1 meds, track your blood sugar with CGM if possible. Look for patterns: do your lows happen after meals? Or in the middle of the night? That could signal thyroid changes.
- Start a Mediterranean-style diet this week. Swap out processed snacks for nuts, add fatty fish twice a week, use olive oil instead of butter.
Evelyn Pastrana
So let me get this straight - I’ve been blaming my fatigue on ‘bad sleep’ and ‘too much coffee’ when it was my thyroid playing hide-and-seek with my pancreas? 😅 Thanks for the wake-up call. I’m booking my TSH test tomorrow.
Arun Kumar Raut
This is so important especially in countries like India where people think diabetes is just about sugar. Thyroid is ignored till it’s too late. I’ve seen my aunt lose hair, gain weight, and get depressed - all blamed on ‘stress’ for years. She had both. Please share this with your family.
Carina M
While I appreciate the effort to disseminate medical information, the casual tone and lack of citations from peer-reviewed journals undermines the credibility of this piece. The American Diabetes Association does not endorse ‘Mediterranean diet’ as a primary intervention for thyroid dysfunction - it is, at best, an ancillary measure. One must not conflate correlation with causation, nor substitute anecdotal Reddit testimonials for clinical evidence.
William Umstattd
THIS IS A LIFESAVING POST. I spent two years being told my brain fog was ‘anxiety’ and my insulin resistance was ‘poor discipline.’ Turns out? My TPOAb was through the roof. My endo didn’t even order antibodies. I almost died from a silent hypoglycemic episode. If you have diabetes and feel ‘off’ - GET TESTED. Not tomorrow. TODAY. Your life depends on it.
Elliot Barrett
Wow. Another ‘you’re not alone’ post that sounds like a sponsored ad for CGMs and thyroid meds. I’ve had Type 2 for 12 years and never had thyroid issues. Maybe stop scaring people with stats that don’t apply to everyone?
Ajit Kumar Singh
Bro this is real I had same thing in 2021 I was losing hair like crazy and my sugar was all over the place doc said its diabetes but I knew something was wrong I asked for TSH and boom hypothyroidism I was on 60 units insulin now I take 35 and I feel like a new person I wish more doctors in India knew this
Maria Elisha
I’m just here because my mom sent me this. I’m 23 and have Type 1. I’ve been feeling tired since middle school. I thought it was just… being a teen. I’m getting tested next week. Fingers crossed.
Andrea Beilstein
It’s funny how we treat symptoms like enemies instead of signals. Diabetes and thyroid aren’t two separate battles - they’re two voices of the same broken system. We’ve been taught to fix numbers, not bodies. But the body doesn’t speak in HbA1c or TSH. It speaks in fatigue, in hair, in cold hands. We just stopped listening.
Lisa Whitesel
Another person with a blog post pretending to be a doctor. You mention ‘2025 NIH study’ like it’s gospel. Where’s the DOI? The journal? The sample size? This isn’t medicine - it’s fear marketing dressed as advocacy.
Courtney Black
Think about it - if your body’s chemistry is out of whack, why are we still blaming willpower? Why do we assume that if you’re tired and gaining weight, you just didn’t try hard enough? What if the problem isn’t you - but the way we’ve been taught to see health? The thyroid isn’t a bonus organ. It’s the thermostat. And when it’s broken, no amount of kale will fix it.
Anna Roh
Yeah yeah I’ve heard this before. I’ll get my blood work done when I feel like it. My doctor says I’m fine. End of story.
Tim Tinh
Man I wish I’d read this 5 years ago. I was on 80 units of insulin and still spiking. Turned out my T3 was half of normal. Doc never checked. I started walking daily, switched to olive oil, and boom - my A1c dropped from 9.2 to 6.8 in 4 months. You’re not broken. You just need the right puzzle pieces. Don’t give up.
Shubham Mathur
Bro I’m from India and this is so true here doctors don’t test thyroid unless you’re screaming for it I had a friend who lost 20kg in 3 months and was told she had ‘diabetes with anxiety’ turns out she had Graves’ disease and was almost in thyroid storm I’m sharing this with every diabetic I know
Ryan Brady
USA is overmedicalizing everything now 😒 I had diabetes for 10 years, never had thyroid issues, and I’m fine. Stop pushing tests on people who don’t need them. Also why is everyone eating fish now? 🐟 #America