Diabetes tests — A1c, albumin/creatinine ratio and other tests

Why are tests important?

Diabetes is a "silent" disease — the patient may feel well even though blood sugar or blood pressure has been elevated for years and is damaging blood vessels and organs. Symptoms (deteriorating vision, foot ulcers, kidney failure) only appear when complications are already advanced. That is why regular monitoring through tests is the only way to objectively assess your condition and adjust treatment in time.

HbA1c (glycated haemoglobin)

HbA1c is the most important diabetes monitoring test. It shows your average blood sugar over the past 2–3 months. The principle: haemoglobin (a protein in red blood cells) is in constant contact with blood glucose. The higher the glucose, the more it "sticks" to haemoglobin, forming HbA1c. Since red cells live for about 120 days, HbA1c reflects average blood sugar over the past few months.

HbA1c values and their meaning

• < 6.0% — normal
• 6.0–6.4% — prediabetes
• ≥ 6.5% — diabetes (diagnosis)
• < 7.0% — target for most diabetes patients
• < 6.5% — stricter target for younger patients in early disease
• < 8.0% — more lenient target for older patients with multiple complications

We recommend measuring HbA1c every 3–6 months. With good treatment adherence, every six months is enough; during treatment changes or poorly controlled diabetes — every 3 months.

What does HbA1c mean in blood sugar values?

• HbA1c 6% ≈ average glucose 7 mmol/L
• HbA1c 7% ≈ 8.6 mmol/L
• HbA1c 8% ≈ 10.2 mmol/L
• HbA1c 9% ≈ 11.8 mmol/L
• HbA1c 10% ≈ 13.4 mmol/L

Every 1% rise in HbA1c corresponds to roughly 1.5 mmol/L higher average blood sugar.

Limitations

HbA1c is not always fully reliable. It can be inaccurate in the following cases:

• Anaemia — the most common reason, lowers HbA1c
• Haemoglobinopathies (sickle cell anaemia, thalassaemia)
• Recent bleeding, blood transfusion
• Chronic kidney failure
• Pregnancy — we prefer other tests (fasting glucose, OGTT)

That is why we always evaluate HbA1c together with other tests and, when needed, also measure blood sugar at home with a glucometer or CGM.

Albumin/creatinine ratio (UACR)

UACR is the most sensitive test for detecting early diabetic nephropathy (kidney damage). In healthy kidneys the glomeruli are "tight enough" to keep proteins (such as albumin) in the bloodstream. When high blood sugar damages the glomerular walls, albumin starts leaking into the urine — the first sign of diabetic nephropathy.

UACR values

• < 3 mg/mmol (< 30 mg/g) — normal
• 3–30 mg/mmol (30–300 mg/g) — microalbuminuria (early nephropathy)
• > 30 mg/mmol (> 300 mg/g) — macroalbuminuria (overt nephropathy)

The test is performed on a single urine sample (preferably the first morning urine). One positive result is not enough for diagnosis — confirmation requires 2 positive tests within 3–6 months. We recommend UACR for all diabetes patients once a year.

Serum creatinine and eGFR

Creatinine is a waste product of muscle metabolism filtered out of the blood by the kidneys. From the serum creatinine level we calculate the eGFR (estimated glomerular filtration rate), which shows how well the kidneys are filtering:

• eGFR > 90 mL/min — normal
• eGFR 60–89 — mild decline
• eGFR 45–59 — moderate kidney failure (stage 3a)
• eGFR 30–44 — more severe kidney failure (stage 3b)
• eGFR 15–29 — severe kidney failure (stage 4)
• eGFR < 15 — end stage (requires dialysis)

Lipid profile

Patients with diabetes often have dyslipidaemia — elevated cholesterol levels. This is one of the biggest risk factors for heart attack. We measure once a year:

• Total cholesterol — < 4.5 mmol/L
• LDL cholesterol ("bad") — < 2.6 mmol/L in diabetes patients (< 1.8 mmol/L if complications are already present)
• HDL cholesterol ("good") — > 1.0 mmol/L in men, > 1.3 mmol/L in women
• Triglycerides — < 1.7 mmol/L

If LDL is high, a statin (atorvastatin, rosuvastatin) is usually needed — it significantly reduces the risk of heart attack and stroke.

Fasting and random blood glucose

• Fasting glucose — after 8 hours of fasting. Normal < 5.6 mmol/L; prediabetes 5.6–6.9; diabetes ≥ 7.0.
• Random glucose — measured at any time. For diabetes diagnosis ≥ 11.1 mmol/L together with symptoms.

Oral glucose tolerance test (OGTT)

OGTT is the "gold standard" for diagnosing diabetes. First, fasting glucose is measured (from venous blood), then the patient drinks 75 g of glucose and 2 hours later venous blood glucose is measured again. Diabetes is diagnosed when the 2-hour value is ≥ 11.1 mmol/L. It is also used to diagnose gestational diabetes (at 24–28 weeks of pregnancy).

Other important tests

• TSH (thyroid function) — once a year, as thyroid disease is more common in diabetes patients
• Vitamin B12 — especially in patients taking metformin, since this drug can cause B12 deficiency
• Liver enzymes (ALT, AST) — to assess fatty liver
• Complete blood count — to rule out anaemia

At our clinic

At Tallinn Endocrinology Clinic we offer all of these tests. With a referral from your health insurance the tests are free of charge.

Paid packages:

• Visit + 4 tests (HbA1c, LDL, HDL, creatinine) — €105
• Visit + HbA1c + retinal photography — €110
• Individual tests (biochemistry / hormones) — €15 each
• Oral glucose tolerance test (incl. test drink) — €40