How to read your diabetes blood test, value by value

You have two pages of abbreviations and a column of numbers in front of you. You have been told the "sugar is a bit high". Let us read that sheet in full, because there are values on it that say far more about your health than glucose itself.

The two sugar values

Fasting glucose

Your glucose after 8 hours without food. It is a snapshot of one moment: it can rise after a bad night, from stress, or from eating late.

HbA1c

The summary of your last two to three months. Far more informative than the previous one, because it does not depend on how you slept last night.

Watch out for the two units. Many laboratories print both on the same sheet, and seeing a "48" next to a "6.5" baffles anybody: they are the same value expressed two ways. If you are only given the big number, divide it by 10.929 and add 2.15.

I develop this fully in HbA1c: what it is and how to lower it, including the important part about when this value misleads you.

Glucose after eating

It does not usually appear on a routine blood test, but if you test at home it is the value you will see most, and almost nobody explains how to read it:

Two important warnings. First: a high reading after eating does not diagnose diabetes on its own — that is what the 75 g oral glucose tolerance test is for. Second: there is no official prediabetes range after eating, so do not exhaust yourself looking for one. Full details in blood sugar after eating.

The four heart values

In type 2 diabetes, cardiovascular risk is a central part of the problem, not a separate matter. That is why these are requested.

LDL cholesterol

The one that deposits in your arteries. In people with diabetes the targets are stricter than for the general population, and depend on your overall risk: those at high risk usually aim below 70 mg/dL, and at very high risk lower still. Your doctor sets that target for your case — there is no single number valid for everyone.

Triglycerides

Above 150 mg/dL they are considered high. They rise frequently in type 2 diabetes, and they respond very well to three specific things: losing weight, cutting alcohol and cutting liquid sugar. Losing excess weight and moving more can bring them down by 20–50 %, according to the American Heart Association.

HDL cholesterol

The "good" one. You want it above 40 mg/dL in men and 50 in women. It rises mainly with exercise.

Blood pressure

It is not on the blood test but it is measured at the same visit, and in diabetes it weighs as much as glucose for long-term risk.

The four nobody looks at (and they say the most)

This is the part of the article I would ask you to read carefully.

Liver enzymes: ALT and AST

If ALT is raised and you do not drink alcohol, by far the most frequent cause is fatty liver. And fatty liver is not an incidental finding in type 2 diabetes: it is at the centre of the mechanism. It is liver fat that makes you release glucose when you should not.

The good news is that liver fat is among the first to go when you start losing weight; on supervised very-low-calorie diets, within a few weeks.

Estimated glomerular filtration rate (eGFR)

How your kidneys are working. Above 90 is considered normal; below 60 sustained over time indicates chronic kidney disease and changes treatment decisions. Between 60 and 89 can be normal for your age. And even above 60, a high urine albumin already indicates kidney damage. Diabetes is one of the leading causes of kidney damage, and that damage gives no symptoms until very late. This number deserves your attention even if nobody has pointed it out.

Urine albumin-to-creatinine ratio

This is the one almost nobody knows they have, and probably the earliest warning of all. It detects small amounts of protein in urine, long before filtration is affected.

If you have diabetes and it has never been requested, ask. It is recommended at least once a year.

Vitamin B12, if you take metformin

Metformin can reduce vitamin B12 absorption with long-term use. Deficiency causes tiredness and tingling in feet and hands — symptoms easily attributed to the diabetes itself. If you have been on metformin for years, it is worth checking.

What to ask at your next appointment

1. "What is my HbA1c target?" It is not the same for everyone: it depends on age, duration and other conditions.
2. "Has my urine albumin been checked this year?"
3. "How is my kidney function?"
4. "Do my liver enzymes suggest fatty liver?"
5. "If I lose weight and improve, how do we adjust the medication?" — this is the key one, and it should be asked beforehand, not once you are already having hypos.

How to keep your results

A simple piece of advice almost nobody follows: keep them all together and ordered by date, with four columns — glucose, HbA1c, weight and waist. A two-year trend says infinitely more than today's sheet, and it will carry you through the months when it looks like nothing is happening.