Does Diabetes Make You Tired? Blood Sugar, Metformin and When to See a GP (UK)

Does diabetes make you tired? What the NHS says

Yes. Tiredness is one of the four main symptoms the NHS lists for both type 1 and type 2 diabetes. On its own it could be many things, but tiredness together with thirst, peeing a lot and weight loss is a reason to get checked.

iIf you think you or your child could have type 1 diabetes, the NHS says see a GP urgently or call 111 (see when to get help). For other common causes of tiredness, see why am I always tired?

Why does diabetes make you tired?

There’s usually more than one reason. A review of the research describes diabetes fatigue as having physical, psychological and lifestyle causes that often overlap.

• High blood sugar. The NHS lists feeling weak or tired as a symptom of high blood sugar.
• Low blood sugar. Tiredness or weakness is a sign of a hypo, mainly in people taking insulin or some tablets.
• Broken sleep. Peeing more at night means waking more. See waking up to pee at night.
• Sleep apnoea. It causes daytime tiredness and is linked with type 2 diabetes. See below.
• Low vitamin B12. Long-term metformin can lower B12 levels, which can make you very tired.
• Mood and stress. Living with a long-term condition is hard work. See low mood.
• Something else. An underactive thyroid, low iron or another medicine. Your GP can check.

Can high blood sugar make you tired?

Yes. The NHS lists feeling weak or tired as a symptom of high blood sugar (hyperglycaemia), along with feeling very thirsty, peeing a lot, blurred vision and losing weight. Symptoms usually come on gradually. Being unwell, stress, missed doses, steroids or eating a lot of sugary or starchy food can all push blood sugar up.

The NHS says call 999 or go to A&E if you think you have high blood sugar and you feel drowsy or struggle to stay awake, feel or are sick, have stomach pain, are breathing faster, have fruity-smelling breath, feel confused or have high ketones. These can be signs of diabetic ketoacidosis. Don’t drive yourself.

Can low blood sugar make you tired?

Yes. Low blood sugar (a hypo) usually means a level below 4mmol/L. The NHS lists tiredness or weakness among its symptoms, with hunger, sweating, shaking, dizziness, tingling lips, a racing heartbeat, irritability, blurred vision and confusion. Hypos are most common with insulin and with tablets such as gliclazide and glimepiride.

If you have diabetes and a reading below 4mmol/L, the NHS advice is to have a fast-acting sugar such as a small sugary drink or glucose tablets, recheck after 10 to 15 minutes, then eat something longer-lasting once you’re above 4mmol/L. Call 999 if someone isn’t responding normally. Tell your GP or diabetes team if you have hypos at night or often.

Does metformin make you tired?

Not usually directly, but long-term use can lower vitamin B12, which can make you very tired. In 2022 the MHRA said reduced B12 is a common side effect of metformin, affecting up to 1 in 10 people, and that the risk rises with higher doses and longer treatment. Your doctor can check your B12 levels.

The MHRA says get advice if you have new or worse extreme tiredness, a sore and red tongue, pins and needles, or pale or yellow skin. It also says metformin can usually continue while B12 is corrected, and not to stop it without speaking to your doctor. See vitamin B12 deficiency symptoms and peripheral neuropathy.

Rarely, metformin can cause lactic acidosis. The NHS says it can make you feel severely tired, with vomiting, stomach pain, muscle cramps and breathing problems. Call 999 if you think you have it. Weight-loss injections can also cause tiredness: see does Mounjaro make you tired? and does Wegovy make you tired?

Diabetes, sleep and sleep apnoea

Sleep apnoea is when breathing stops and starts while you sleep. The NHS lists daytime tiredness, poor concentration and morning headaches as signs, and type 2 diabetes among the problems that untreated sleep apnoea can lead to. Obesity is a shared risk factor, so the two often turn up together.

iIf you snore loudly, or someone has heard you gasp or choke in your sleep, tell your GP. The NHS says you may need to tell the DVLA, and you must not drive until excessive sleepiness is under control. See sleep apnoea, sleep and weight and how to stay awake when tired.

When to see a GP or get urgent help

iIf you take insulin, check the DVLA rules on GOV.UK: you must tell the DVLA about disabling hypos. Never stop or change a diabetes medicine without speaking to your GP, diabetes team or pharmacist.

Supplements with diabetes: check first

No supplement treats diabetes or replaces your medicines. Some supplements can affect blood sugar or interact with diabetes medicines, so check with your GP, diabetes team or pharmacist before you start one. Berberine, for example, is sold as a supplement but can add to the effect of diabetes medicines: see berberine.

CBD questions: in the only placebo-controlled trial in type 2 diabetes, CBD didn’t improve blood sugar control. See CBD and diabetes.

Our pick

Magnesium Glycinate Sleep Complex

if your GP or pharmacist is happy, the Magnesium Glycinate Sleep Complex is a berry drink powder with 290mg of magnesium (77% NRV) per 4.75g serving, from bisglycinate and citrate, sweetened with stevia. Magnesium contributes to a reduction of tiredness and fatigue and to normal energy-yielding metabolism. It doesn’t treat diabetes. If you have diabetes, check with your GP or pharmacist before taking supplements.

Add Magnesium Glycinate Sleep Complex to bag See ingredients and reviews

Subscribe and save 25% on your first order, then 20%. New to Evopure? Join our emails for 20% off a one-off first order. Free UK delivery over £45. Vegan and made in the UK.

Subscribe £22.49One-off £29.99

View product

Our Reishi Mushroom Adaptogenic Complex isn’t suggested here: its pack says it isn’t for people on medication, and it contains coconut sugar. For more on magnesium and tiredness, see magnesium for energy.

iIf you take any regular medicines, check with your GP or pharmacist first. We don’t recommend our products during pregnancy or breastfeeding. For adults (18+) only.

See also does high cholesterol make you tired?