A1C Calculator
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Enter your average blood glucose to estimate your A1C, or enter your A1C to estimate your average blood glucose.



Nutrita’s A1C calculator allows you to estimate your A1C based on your blood sugar levels, and vice versa. All you have to do is to measure your blood sugar and enter it into the calculator.

However, a single measurement cannot accurately predict your A1C because the blood sugar level of several months determines the A1C. Furthermore, your blood sugar fluctuates during the day, which you have to take into account. If you have diabetes, you are likely to experience the dawn phenomenon[3]. Early in the morning, the body releases stress hormones, which is totally normal. It raises blood sugar levels to provide you with energy to start the day. In healthy individuals, this is counteracted by insulin. If you have diabetes, insulin has a harder time getting sugar into your cells, and the blood sugar increase can be substantial. The morning blood sugar is, however, not representative for your overall blood sugar during the rest of the day.

To get a reasonable estimate of your A1C, you need your blood sugar levels at different times of the day and over a more extended period. This does not mean that you have to manually measure your blood sugar several times a day for several weeks. But you need to know how much it fluctuates during the day. You can then regularly measure and enter the values into the calculator.

Ideally, you would know exactly what your blood sugars are doing by using a continuous glucose monitor (CGM). They can currently sample blood sugar levels every 5 minutes in a portable, non-invasive manner.

The only sustainable way to lower your A1c is nearly always a question of removing the fat digestible sugars (e.g. flour products, added sugars), your total carb intake and removing high omega 6 seed oils[3][4]. If you are serious about getting it down quickly, the best option would be to follow a strict keto diet.

A keto diet eliminates all grains, added sugars, and starchy vegetables. Fruit is very restricted, some berries are allowed from time to time. Instead, you focus on meat, fish, eggs, low-carb vegetables and nuts. This sounds like a significant change when you are used to the typical American diet, but it offers a variety of healthy, nutrient-dense and delicious options.

Nutrita will help you to make the best food choices. The carnivore diet falls within the ketogenic spectrum and is a suitable option.

If you want to go one step further, you can combine the keto diet with intermittent fasting. Not eating for most of the day is an excellent way to bring your blood sugars down. It might seem intimidating initially, but it will be easy once you are keto-adapted. The keto diet is very satiating and also keeps your blood sugar stable. Sudden drops in blood sugar are counterproductive to a stable mood and feeling energized which is often what people experience on a high-carb diet Western diet.

Check out on out intermittent fasting guide for more information.

Lastly, if you want to get your A1c down prolonged fasting (> 24 hours) is an option but best undertaken with the care of a medical professional[5]. Extended fasting reverses fatty liver in no time, a driver of insulin resistance[6][7].

If you have diabetes or taking any medications, you have to consult your doctor before making any dietary changes. Because the suggested approaches are so powerful in lowering your blood sugar, you are at risk of hypoglycemia (very low blood sugar) if you don’t adjust the dose of blood-sugar lowering medications. This can be dangerous so make sure you seek your doctor’s advice.

Because hemoglobin has a half-life of around 4 months, a change in diet will not immediately affect the A1C value. The A1c reflects the blood sugar of the last 2 – 3 months. After going on a low-carb diet, you should wait for at least 2 months before measuring A1C, if you want to get a meaningful value.

How fast A1c goes down depends on several factors. First of all on your carb intake. The fewer carbs you eat, the faster the A1C will go down.

Secondly, it depends on your level of insulin resistance. When you are highly insulin resistant or even diabetic, the blood sugar does not immediately go down upon carb restriction. Your body has stored a lot of sugar, and once insulin levels drop, the sugar is released.

Even if you don’t see immediate effects, a low-carb or ketogenic diet is the way to go. It may take a little while, but your blood sugar and A1c values will go down. Nutrita is here to help you to achieve your goal as soon as possible.

Changing your diet as to reduce your total carb intake and only remove junk carbs (e.g. fruit juice, bread, pizza) is the most sustainable way to lower your blood sugar and A1C long-term. There are, however, some blood sugar-lowering dietary supplements that can support you achieving your goal.


Lysuline is a new dietary supplement thought to be beneficial for people with prediabetes or type 2 diabetes. It contains the amino acid lysine, the mineral zinc and vitamin C, each of which are known to lower blood glucose individually. What might they do in combination? One study showed that lysuline treatment can significantly lower HbA1c levels within two weeks[8].


Berberine is one of the most effective supplements for blood glucose reduction. It lowers blood sugar by stimulating glucose uptake and inhibiting gluconeogenesis (your body’s own sugar production)[9]. A meta-analysis has shown that berberine effect on blood sugar is comparable to Metformin[10].

Salacia reticulata

Salacia reticulata lowers blood sugar by inhibiting the absorption of carbohydrates. Three studies are consistent in showing that the supplement significantly reduces the blood sugar rise after a meal[11][12][13].

Gynostemma pentaphyllum

Gynostemma pentaphyllum is a traditional Vietnamese herb that can be used to make tea. It lowers blood sugar by stimulating glucose uptake. The supplement has not been studied extensively, but the few studies that have been performed showed a significant and robust decrease in fasting glucose and HbA1C[14][15].

HbA1c is a useful marker to estimate long-term blood sugar levels. That’s an advantage over fasting glucose tests or oral glucose tolerance tests (OGTT) because these tests can only measure the blood sugar at a specific time point, which is prone to high fluctuations.

One problem with A1c is that it is influenced by the lifetime of red blood cells. On average, red blood cells from healthy people with lower and more stable blood glucose levels live longer than the ones from diabetic patients. With a shorter life cycle, hemoglobin has less time to become sugar-bound the HbA1c may be lower than expected, based on the blood sugar level[16].

The lab result is more accurate if the person falls within the average turnover rate. But it may be overestimated or underestimated if their red blood cell turnover is faster or slower, respectively[17].

A person’s red blood cell turnover rate can be influenced by the following

  • malaria
  • chronic anemia
  • major blood loss
  • hemolysis
  • uremia
  • pregnancy
  • smoking
  • various infections

Another limitation with A1c as a marker for diabetes is that such increases in blood sugar levels are a rather late event on the path to diabetes. You may already have a high level of insulin resistance and be oversecreting insulin, but as long as your pancreas produces sufficient amounts of insulin to keep your blood sugars in range, your HbA1c will be relatively low.

Controlling your A1c by injecting insulin or having your pancreas secrete lots of insulin to cover carb-rich meals worsens outcomes in diabetics[18].

HbA1c is not useful to prevent diabetes nor to monitor progress when using insulin injections. However, it is useful to see whether or not you’re an outright diabetic or if you’re reversing it successfully with dietary changes.

It’s not a very accurate measure but it can be directionally accurate; it can tell you if you’re diabetes is improving or worsening but it can’t say by how much accurately.

HbA1c gives an average blood glucose level over 3 months which cannot take account blood glucose variability. Two people can have the same HbA1c level but differ significantly in how widely their blood sugars rise and fall throughout the day.

The stability or lack thereof characterized by a rise and fall in blood sugars is important; less variability, more stability is healthier[19].



To see how far or close you are to the diabetic state, you may want to consider the McAuley index. It’s a diabetes relevant estimate of metabolism, but this time of insulin resistance more specifically. See our insulin guide for more information on how to benefit from using this index.