Feeling tired all the time is one of the most common yet overlooked symptoms of type 2 diabetes. This persistent exhaustion differs from ordinary tiredness—it's a profound fatigue that doesn't improve with rest and can significantly affect your work, relationships, and daily activities. The connection between type 2 diabetes and constant tiredness is complex, involving blood sugar fluctuations, metabolic changes, and often other medical conditions. Understanding why diabetes causes fatigue and recognising when to seek help are essential first steps. With appropriate blood glucose management, lifestyle changes, and medical support, many people experience substantial improvements in their energy levels and overall quality of life.

Why Type 2 Diabetes Makes You Feel Tired All the Time

Persistent fatigue is one of the most common and debilitating symptoms experienced by people living with type 2 diabetes. This overwhelming tiredness differs from ordinary fatigue—it's a profound exhaustion that doesn't improve with rest and can significantly impact daily functioning, work performance, and quality of life.

The relationship between type 2 diabetes and fatigue is multifactorial and complex. At its core, diabetes affects how your body processes glucose, the primary fuel source for cells throughout your body. When this system malfunctions, your cells struggle to access the energy they need, leaving you feeling persistently drained. Additionally, the metabolic disturbances associated with diabetes can trigger inflammatory processes and hormonal changes that may further contribute to exhaustion.

Tiredness is widely reported by people with type 2 diabetes and is more prevalent than in the general population. This fatigue isn't simply a minor inconvenience—it's associated with reduced physical activity, poorer diabetes self-management, increased risk of depression, and diminished overall wellbeing. Understanding the underlying mechanisms is essential for effective management.

The good news is that diabetes-related fatigue is not inevitable. With appropriate blood glucose control, lifestyle modifications, and medical support, many people experience significant improvements in their energy levels. Recognising fatigue as a legitimate symptom rather than something to simply endure is the first step towards addressing it effectively and regaining vitality in daily life.

Blood Sugar Levels and Persistent Fatigue

Blood glucose fluctuations represent the most direct cause of fatigue in type 2 diabetes. Both hyperglycaemia (high blood sugar) and hypoglycaemia (low blood sugar) can leave you feeling exhausted, though through different mechanisms.

Hyperglycaemia and energy depletion: When blood glucose levels remain consistently elevated, your cells cannot effectively absorb glucose despite its abundance in the bloodstream. This occurs because of insulin resistance—the hallmark of type 2 diabetes—where cells become less responsive to insulin's signal to take up glucose. Consequently, your cells are essentially starving for fuel whilst glucose accumulates in your blood. Your kidneys attempt to eliminate excess glucose through increased urination (polyuria), which can lead to dehydration, further compounding fatigue. Additionally, chronic hyperglycaemia triggers oxidative stress and inflammation, both of which may contribute to feelings of exhaustion.

Hypoglycaemia and energy crashes: Conversely, when blood glucose drops too low—most commonly in people taking insulin or sulfonylureas (such as gliclazide), or due to delayed meals or excessive physical activity—your brain and muscles are deprived of their primary energy source. This triggers symptoms including profound tiredness, difficulty concentrating, shakiness, and weakness. Even mild hypoglycaemic episodes that don't produce obvious symptoms can contribute to persistent fatigue.

The importance of glucose stability: Frequent swings in blood sugar between high and low levels can contribute to fatigue. Achieving stable glucose levels through appropriate medication, regular meals, and lifestyle modifications often results in substantial improvements in energy levels and overall wellbeing. If you experience symptoms of hyperglycaemia or hypoglycaemia, consult the NHS guidance on high blood sugar and low blood sugar for advice on when to seek help.

Other Medical Causes of Tiredness in Type 2 Diabetes

Whilst blood glucose disturbances are primary contributors to fatigue, several other medical conditions commonly associated with type 2 diabetes can cause or worsen tiredness.

Anaemia: People with diabetes have increased risk of anaemia, particularly iron deficiency anaemia and anaemia of chronic disease. Diabetes-related kidney disease (diabetic nephropathy) can impair production of erythropoietin, a hormone essential for red blood cell formation. Certain diabetes medications, particularly metformin when used long-term, can interfere with vitamin B12 absorption, potentially leading to megaloblastic anaemia. The MHRA advises that vitamin B12 levels should be monitored in people on long-term metformin, especially if anaemia or peripheral neuropathy develops. Both iron deficiency and B12 deficiency reduce oxygen delivery to tissues, causing fatigue, weakness, and reduced exercise tolerance.

Thyroid dysfunction: Thyroid disorders, particularly hypothyroidism (underactive thyroid), occur more frequently in people with diabetes. An underactive thyroid slows metabolism throughout the body, causing profound fatigue, weight gain, cold intolerance, and cognitive sluggishness. NICE guidance recommends thyroid function testing in people who experience unexplained fatigue or other symptoms suggestive of thyroid disease. (Note: autoimmune thyroid disease is classically more strongly associated with type 1 diabetes.)

Sleep disorders: Obstructive sleep apnoea (OSA) is common in people with type 2 diabetes, particularly those who are overweight. This condition causes repeated breathing interruptions during sleep, leading to poor sleep quality, daytime sleepiness, and fatigue. Additionally, nocturia (frequent nighttime urination) related to poor glucose control or certain medications (such as SGLT2 inhibitors or diuretics) disrupts sleep quality.

Depression and mental health: Depression is twice as common in people with diabetes compared to the general population. The relationship is bidirectional—diabetes increases depression risk, whilst depression worsens diabetes control. Fatigue is a core symptom of depression and can be difficult to distinguish from diabetes-related tiredness. Anxiety disorders, which are also more prevalent in diabetes, contribute to exhaustion through chronic stress and hypervigilance.

Cardiovascular disease: Type 2 diabetes significantly increases cardiovascular disease risk. Heart failure, coronary artery disease, and peripheral vascular disease all cause fatigue through reduced cardiac output and impaired tissue perfusion. Fatigue may be an early warning sign of cardiovascular complications requiring investigation.

When to See Your GP About Diabetes Fatigue

Whilst some degree of fatigue is common with type 2 diabetes, certain situations warrant prompt medical evaluation. Recognising when tiredness requires professional assessment is crucial for identifying treatable causes and preventing complications.

Seek urgent or emergency medical attention if you experience:

• Severe or sudden-onset symptoms: Call 999 or go to A&E immediately if you have severe chest pain, severe breathlessness, confusion or drowsiness, signs of severe dehydration, or suspected severe hypoglycaemia that does not respond to treatment. These may indicate serious complications including hyperosmolar hyperglycaemic state, cardiovascular events, or severe low blood sugar.

• Urgent advice: Use NHS 111 for urgent but non-emergency advice if you're unsure whether your symptoms require immediate attention.

See your GP if you experience:

• Fatigue despite good glucose control: If you're maintaining blood glucose levels within your target range but continue experiencing debilitating tiredness, this suggests other underlying causes requiring investigation. Your GP should evaluate for anaemia, thyroid dysfunction, vitamin deficiencies, sleep disorders, or other medical conditions.

• Progressive worsening: Fatigue that steadily intensifies over weeks or months may indicate deteriorating diabetes control, developing complications, or concurrent medical conditions. Don't dismiss this as simply "getting older" or an inevitable consequence of diabetes.

• Associated symptoms: Fatigue accompanied by unexplained weight loss, increased thirst and urination, recurrent infections, slow wound healing, or changes in vision suggests inadequate diabetes control requiring medication adjustment. Fatigue with low mood, loss of interest in activities, or thoughts of self-harm indicates possible depression requiring mental health support.

What to expect at your appointment: Your GP will likely review your recent blood glucose readings, assess your current diabetes management, and perform a physical examination. Blood tests typically include HbA1c (average glucose control over 2–3 months), full blood count (for anaemia), ferritin and iron studies (for iron deficiency), vitamin B12, thyroid function, kidney function (including urine albumin:creatinine ratio), and lipid profile. Depending on findings, further investigations such as sleep studies or cardiac assessment may be recommended. Be prepared to discuss your fatigue pattern, sleep quality, mood, medication adherence, and how tiredness affects your daily life.

Managing Tiredness With Type 2 Diabetes

Addressing diabetes-related fatigue requires a comprehensive approach targeting multiple contributing factors. Evidence-based strategies can significantly improve energy levels and quality of life.

Optimise blood glucose control: Achieving stable glucose levels within your individualised target range is fundamental. Work with your diabetes care team to review your medication regimen, ensuring it effectively controls glucose whilst minimising the risk of hypoglycaemia, particularly if you take insulin or sulfonylureas. NICE recommends HbA1c targets that are individualised: typically 48 mmol/mol (6.5%) for adults managed by lifestyle and diet or a single drug not associated with hypoglycaemia; 53 mmol/mol (7.0%) for those on drugs that can cause hypoglycaemia (such as insulin or sulfonylureas); and higher targets may be appropriate for people with frailty, comorbidities, or a history of severe hypoglycaemia. Your diabetes team may also consider treatment intensification if HbA1c rises to 58 mmol/mol (7.5%) or above.

Blood glucose monitoring: Self-monitoring of blood glucose is not routinely recommended for all people with type 2 diabetes. NICE advises targeted monitoring for those on insulin, sulfonylureas, during intercurrent illness, when treatment changes, or if driving. Flash or continuous glucose monitoring may be available on the NHS for adults with type 2 diabetes who are on insulin therapy and meet specific NICE criteria. Discuss with your diabetes team whether monitoring would be helpful for you.

Dietary modifications: Eating regular, balanced meals helps maintain stable blood glucose and sustained energy. Focus on lower glycaemic index carbohydrates (wholegrains, pulses, vegetables) that release glucose gradually, combined with adequate protein and healthy fats. A regular meal pattern tailored to your individual needs and preferences supports better glycaemic control. Stay well-hydrated, as even mild dehydration exacerbates tiredness.

Physical activity: Though counterintuitive when feeling exhausted, regular physical activity is one of the most effective interventions for diabetes-related fatigue. Exercise improves insulin sensitivity, stabilises glucose levels, enhances cardiovascular fitness, and boosts mood. Start gradually with activities you enjoy—even 10-minute walks—and progressively increase duration and intensity. NICE recommends at least 150 minutes of moderate-intensity activity weekly for people with type 2 diabetes. The NHS provides guidance on physical activity for adults.

Sleep hygiene: Prioritise 7–9 hours of quality sleep nightly. Establish consistent sleep and wake times, create a cool, dark sleeping environment, and avoid screens before bedtime. If you suspect sleep apnoea (loud snoring, witnessed breathing pauses, morning headaches, excessive daytime sleepiness), discuss this with your GP, as treatment with continuous positive airway pressure (CPAP) can dramatically improve energy levels.

Address contributing conditions: Ensure any identified medical causes of fatigue receive appropriate treatment. This may include iron or vitamin B12 supplementation for anaemia, levothyroxine for hypothyroidism, or psychological interventions for depression. Regular medication reviews help identify drugs that may contribute to tiredness.

Structured education and support: Consider attending a structured diabetes education programme such as DESMOND (Diabetes Education and Self-Management for Ongoing and Newly Diagnosed), which is available through the NHS. These programmes can improve both psychological wellbeing and diabetes outcomes.

Stress management: Chronic stress worsens both diabetes control and fatigue. Consider evidence-based approaches such as mindfulness or cognitive behavioural therapy.

Reporting side effects: If you experience side effects from your diabetes medications, including persistent fatigue, discuss this with your healthcare team. You can also report suspected side effects through the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk.

Remember that managing diabetes-related fatigue is a gradual process requiring patience and persistence, but meaningful improvements are achievable with appropriate support and self-management strategies.

Frequently Asked Questions