← All Conditions
Condition Guide

Diabetes: Understanding Your Blood Sugar Tests

More than 800 million adults worldwide are living with diabetes, and around half are undiagnosed. Here's a complete plain-language guide to what your blood sugar and HbA1c reports actually mean.

Written by Suman Konda, PharmD, Clinical Pharmacist · Based on peer-reviewed sources · Editorial policy · Not medical advice

Last updated: · How we check our content

Which tests diagnose diabetes?

TestNormalPrediabetesDiabetes
Fasting Blood Sugar<100 mg/dL100–125≥126 mg/dL
Post-meal (2hr PPBS)<140 mg/dL140–199≥200 mg/dL
Random Sugar (with symptoms)<140 mg/dL–≥200 mg/dL
HbA1c<5.7%5.7–6.4%≥6.5%

Diagnosis requires: two abnormal fasting tests on separate days, OR one fasting + one PPBS positive, OR HbA1c ≥6.5% on two occasions.

What other tests do diabetics need?

Once diagnosed with diabetes, your doctor will monitor multiple organ systems that diabetes affects over time:

TestWhy neededHow often
HbA1c3-month average sugar controlEvery 3 months
KFT (Creatinine, eGFR)Diabetic kidney diseaseYearly
Urine MicroalbuminEarliest sign of kidney damageYearly
Lipid ProfileHeart disease riskYearly
LFTFatty liver (common in T2DM)Yearly
Eye examDiabetic retinopathyYearly

What does HbA1c mean in practice?

HbA1c target for most diabetics: below 7%

HbA1c of 7% corresponds to an average blood sugar of about 154 mg/dL. For most Type 2 diabetics, the target is below 7%. For elderly patients or those with frequent hypoglycaemia, a slightly higher target (7.5–8%) may be safer. For young, newly diagnosed patients without complications, aiming for below 6.5% is ideal. Always discuss your personal target with your doctor: it's not one-size-fits-all.

Can Type 2 diabetes be reversed?

Yes: especially in early stages

Type 2 diabetes can be put into remission (HbA1c normalises without medication) with significant weight loss (10–15% of body weight), a low-calorie or low-carbohydrate diet, and regular exercise. This is most achievable in the first 5 years of diagnosis. Even without full remission, lifestyle improvements dramatically reduce complications. Prediabetes is almost always reversible with lifestyle changes alone.

Questions to ask your doctor

  • What is my HbA1c target and am I reaching it?
  • Do I need to check my kidneys, eyes and feet this year?
  • Should I be on a statin for heart protection?
  • Can I reduce my medication with better diet and exercise?

Frequently Asked Questions

What blood tests diagnose diabetes?
Diabetes is diagnosed using HbA1c (48 mmol/mol or above), a fasting glucose of 7.0 mmol/L or more, or a raised result on a glucose tolerance test, usually confirmed on a second occasion.
What's the difference between type 1 and type 2 diabetes?
Type 1 is an autoimmune condition where the pancreas makes little or no insulin, usually needing insulin from diagnosis; type 2 involves insulin resistance and is strongly linked to lifestyle and often managed first with diet and tablets.
What is pre-diabetes?
Pre-diabetes means blood sugar is above normal but below the diabetes threshold (HbA1c 42–47 mmol/mol). It's a warning sign, and lifestyle changes at this stage can often prevent progression to type 2 diabetes.

Recognising the symptoms of diabetes

Classic symptoms include increased thirst, passing more urine (especially at night), tiredness, unintentional weight loss, blurred vision and recurrent infections such as thrush. In type 1 diabetes these can develop rapidly over days to weeks, while in type 2 they often build gradually and may be absent for years.

Because type 2 diabetes can be silent, many people are diagnosed through routine blood tests before symptoms appear, which is a good thing, as earlier control reduces long-term complications.

How diabetes is managed

Type 1 diabetes always requires insulin, usually as a basal-bolus regimen or pump, alongside carbohydrate counting. Type 2 diabetes is managed first with diet, weight loss and activity, then with tablets such as metformin, and later with other medicines or insulin if needed.

Across both types, the aim is to keep blood glucose and HbA1c within an individualised target while avoiding hypoglycaemia, and to control blood pressure and cholesterol, which together protect the heart, kidneys, eyes and nerves.

Preventing complications

Well-controlled diabetes greatly reduces the risk of complications, but regular monitoring is essential: HbA1c every few months, annual eye screening, kidney tests (including urine albumin), foot checks, and blood pressure and cholesterol reviews.

For type 2 diabetes, substantial weight loss can even induce remission in some people, particularly early after diagnosis: a major shift in how the condition is understood.

ICD-10-CM diagnosis codes

Diabetes is coded by type and by any documented complication. These are among the most frequently used codes:

ICD-10-CM codeDescription
E11.9Type 2 diabetes mellitus without complications
E11.65Type 2 diabetes mellitus with hyperglycemia
E10.9Type 1 diabetes mellitus without complications
E11.21Type 2 diabetes mellitus with diabetic nephropathy
E11.42Type 2 diabetes mellitus with diabetic polyneuropathy
R73.03Prediabetes

Codes shown are from the current ICD-10-CM classification (FY2026) and are provided for general reference. Clinical coding is performed by trained coders using the full medical record.

References

The clinical information on this page is based on peer-reviewed sources indexed in PubMed, the biomedical literature database of the US National Library of Medicine.

  1. Harreiter J, Roden M. Diabetes mellitus: definition, classification, diagnosis, screening and prevention (update 2019). Wien Klin Wochenschr. 2019;131(Suppl 1):6-15. doi:10.1007/s00508-019-1450-4 · PMID 30980151
  2. Kalra S, Raizada N. Dyslipidemia in diabetes. Indian Heart J. 2023;76(Suppl 1):S80-S82. doi:10.1016/j.ihj.2023.11.002 · PMID 37956957
  3. Type 2 Diabetes. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK513253
  4. Type 1 Diabetes. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK507713

Related reading

Medical Disclaimer: This page is for general educational purposes only and does not constitute medical advice. Always consult a qualified doctor before making any health decisions.