The One Drop Guide to A1C

what is a1c - how to lower a1c - diabetes

A Numbers Game

Living with diabetes means living with numbers. Lots of numbers. Take A1C, for example. What is A1C? The hemoglobin A1C (“HbA1C” or “A1C”) blood test is used to diagnose diabetes and assess how well someone is managing their diet, food, activity, and blood glucose levels.

But what is A1C? What are the A1C ranges that define prediabetes and diabetes? What causes your A1C numbers to rise? How do you convert A1C to average blood glucose?

A1C: The Ultimate Guide

The A1C test is a blood test used to diagnose diabetes and assess how well someone is managing their diabetes. Your A1C value is a number that reflects your average blood glucose (BG) over the past 2-3 months*.

To help better understand all those numbers, we’ve come up with a helpful guide! In it, you can track your numbers with a detailed A1C chart and use set goals for future A1C test results.

Check out the One Drop Guide to A1C for answers to all of your most frequently asked questions and download the High Resolution PDF.


what is a1c


*Red blood cells live 2-3 months, so A1C reflects the hemoglobin’s exposure to glucose over that time.


What is A1C? One Drop Guide to A1C and Diabetes

what is a1c

best diabetes monitor - best diabetes blood glucometer

One Drop | Guide to Handling the Summer Holidays with Diabetes

Do you find it hard to manage your diabetes during the holidays? The holidays are meant to be a time for family, friends, and fun. Unfortunately, for many people with diabetes, they can be very stressful. The meals are large and usually unhealthy. Snacks are bottomless and it feels like you can’t move ten feet without someone offering you more food!

If you’re on track in managing your diabetes, you’ve worked hard to keep your blood glucose in range, exercise, and watch your diet. And you’re not going to let that go!

diabetes management - blood sugar

Keep On Keepin’ On! 

It’s important to avoid, or at least limit, foods that can make your blood sugar skyrocket — mainly carbohydrates (carbs). Carbs are found in many popular holiday foods including pasta, bread, cakes, cookies, and ice cream. The key to staying in range is to plan ahead! Tell yourself you will only have a few bites of something you really want and decide ahead of time how you will deal with social pressure. Remember–you can always just walk away.

Pro-Tip: It takes 20 minutes for you to realize you’re full.

Luckily, staying on track during the festivities is totally possible–it just requires a bit of planning! It’s easy to feel empowered and prepared for the holiday festivities. Here are just a few pointers:

Things to consider if you’re hosting:

❑ Include lots of filling, low carb options such as vegetables and dip, meats, cheese, and nuts.

❑ Avoid sampling more than necessary while cooking.

Download our low carb guide for 40+ food options to serve at your next party! 

Things to consider if you’re a guest:

❑ Bring a healthy dish that you know you can enjoy.

❑ Ask the host beforehand what will be served.

❑ Decide ahead of time how much you will eat and how you will handle social pressure.

Be sure to check out our infographic for our full list of tips on how to stay focused and healthy this season! Summer is such a fun time; don’t miss out on any of it because of diabetes. You’ve got this — we are in it, together! Happy Summer Fun. ☀

diabetes management

diabetes management - blood glucose

One Drop Guide to Checking Blood Sugar

how to check blood sugar - diabetes

Everyone with diabetes needs to check their blood sugar. It can be a pain, but the truth is — it’s one of the best things you can do for your health. Checking your blood sugar lets you know how your body is doing at any point in time and empowers you to make healthy choices at those times.

Believe it or not, there’s a science to it. ⚗ If you’ve just been diagnosed with diabetes, or you need a refresher (we all do at some point!), this guide shows you how to check blood sugar in ways both impactful & insightful.

Download the One Drop Guide to Checking Blood Sugar! 

You Can Only Manage What You Measure

We need to know how to check blood sugar in a structured way so that we can:

👉 Spot trends

👉 Pinpoint problem areas

👉 Make the changes you need to stay in range and on track!

Fun Fact: Studies show that checking blood sugar at regular times throughout the day significantly reduces A1C.

Why and How To Check Blood Sugar

The why

This may seem obvious, but a reminder is always helpful 🙂 At One Drop, we believe the more we check, the better we manage. We see it firsthand, everyday! From those of us here at One Drop who have diabetes, as well as feedback from our One Drop family. When we check often, we’re able to make actionable, data-driven changes to our diabetes management methods. And that’s what we like to call #diabadass.

diabetes management - blood sugar

The how

It’s easy! Here’s how to check blood sugar, just follow these steps:

1️⃣ Wash your hands with soap and water

2️⃣ Insert a test strip into your meter

3️⃣ Prick the side of any fingertip

4️⃣ Squeeze out a drop of blood

5️⃣ Touch the drop to the test strip

6️⃣ Wait a few seconds for the result

To get the best results:

✓Check frequently

✓Analyze your data regularly

✓Make changes as needed

Even More Awesome Pro-Tips

Checking frequently is great! But to get the most out of your glucose data, you need to check at the right times:

— first thing in the morning ☀

blood sugar target between 70mg/dL & 110 mg/dL ( 3.9 mmol/l & 6.1 mmol/l)

— before you eat 🥓

blood sugar target between 70mg/dL & 110 mg/dL (3.9 mmol/l & 6.1 mmol/l)

— 2 hours after you eat 🕘

blood sugar target between 70mg/dL & 140 mg/dL (3.9 mmol/l & 7.8 mmol/l)

— before exercise 🏋️‍♂️

blood sugar target between 70mg/dL & 140 mg/dL (3.9 mmol/l & 7.8 mmol/l)

— after exercise 🕤

blood sugar target between 70mg/dL & 140 mg/dL (3.9 mmol/l & 7.8 mmol/l)

— before bedtime 🛌

blood sugar target between 70mg/dL & 140 mg/dL (3.9 mmol/l & 7.8 mmol/l)

one drop - diabetes

One Drop Guide to Checking Blood Sugar

Check out the full infographic below (or here) to learn everything you need to know about checking glucose. You’ll find plenty of advice about when you should check to get the most insight into how you’re doing. Next, check out our Guide to A1C, which explains how to use all your new blood sugar moments to decipher your A1C!

One Drop Guide to Checking Blood Sugar

diabetes management - blood glucose

Why Doesn’t My Average Blood Glucose Match My A1C?!

Diabetes Bloodwork - A1C

So, you test your meter for accuracy and everything looks good. You take your average blood glucose (BG) and convert it to A1C using a table, calculator, or equation you find online. Then, you get your blood work done and learn that your actual A1C is…

Not even close! What is the deal? 

It turns out, the relationship between average BG and A1C isn’t as clear as most of us think. After doing some research, I came across a couple of reasons why someone’s actual A1C may be higher or lower than expected…

Time Out. Why Use A1C?

But before we get into that, let’s briefly go over why A1C is used to approximate average glucose over ~3 months:

As glucose enters your blood, it attaches to a protein in your red blood cells called “hemoglobin.”

● Hemoglobin is the same protein that carries oxygen in your bloodstream, and it is what gives blood its red color

A1C measures the total amount of glucose that has attached to your hemoglobin over the lifespan of your red blood cells (typically ~3 months).

OK, now that we’ve got the science down, here’s why your average BG and lab-measured A1C values might not match up:

1. BG meter average does not usually reflect the average over a full 24 hours

This reason is pretty obvious. If you are not on a CGM, it’s tough to get a full picture of your average blood glucose throughout the day. We generally check much more during the day than at night, and nighttime glucose values may be very different from daytime values. We also tend to test more often before eating (when glucose is typically lower), and less often after meals (when glucose is typically higher).

Want to learn more about A1C? Download our Guide to A1C here!

So, for most people, BG meter average doesn’t accurately reflect average blood glucose over a full 24 hours. A1C, on the other hand, does.

If you want your BG meter average to better reflect your A1C values, check more often! And make sure you check at various times throughout the day, including 1-3 hours after eating.

2. The Average BG to A1C conversion equation is not perfect

Most (if not all) average BG to A1C conversion tables and calculators use the below equation to estimate A1C:

Average BG (mg/dL) = 28.7 X A1C (%) – 46.7


Diabetes Care - A1C equation

This equation is based on data from a 2008 study of over 500 subjects (268 T1Ds, 159 T2Ds, and 80 non-diabetics) at 10 international centers around the world. The A1C values were all measured in a central laboratory, so differences in laboratory method or technique were not a factor. People were studied for 12 weeks, with two days of CGM and three days of 7-point glucose profiles each week. The BG meters used were carefully standardized and calibrated.

diabetes management - blood sugar

The graph below shows the data used to derive the relationship between average glucose and A1C. As you can see, there is A LOT of scatter. A number of data points are off the trend line by ± 1%. And for some A1C values, the spread is enormous… Check out the range of A1Cs for people with an average glucose of ~110 mg/dL — it goes from below 4% to almost 9%!

So, importantly, the study concluded that the equation could be used to convert A1C to average blood glucose values for “most patients.”  Not all patients, just “most.”

Avg BG v A1CResults of a study of 507 subjects. Published in Diabetes Care 31:1473-1478, 2008.

OK… But why do so many people have A1C values that don’t follow the equation?

Answer: Biological variation.

As it turns out, the biological processes that dictate A1C are not exactly the same for everyone.

The rate that glucose attaches to hemoglobin can vary significantly from person to person:

● For some people, glucose attaches to hemoglobin very quickly. So even if their average blood glucose is 154 mg/dL (which would yield an estimated A1C of 7% using the above equation), their actual A1C may 8% or even higher.

● For others, glucose attaches to hemoglobin very slowly, and for the same average glucose of 154 mg/dL, they may have an actual A1C value in the 6% range or lower.

one drop - diabetes

The rate of red blood cell turnover varies from person to person:

● For some, red blood cells turnover much faster than the typical ~3 months. The faster red blood cells turn over, the less hemoglobin can attach before the red blood cells die, which may lead to a lower-than-expected A1C result.

● For others, red blood cells live much longer than the typical ~3 months. The longer the cells live, the more glucose can attach to the hemoglobin, which may lead to a higher-than-expected A1C result.

Various other factors may also be at play, such as:

● People who give blood, have any internal bleeding, or have some sort of anemia where the red cells break down faster than normal, will lose some older red blood cells with lots of glucose attached to the hemoglobin. As a result, the body will make new red blood cells with glucose-free hemoglobin and the A1C % will be lower than expected.

● People with spleen damage (or whose spleen has been surgically removed) may have more of the older red blood cells, because the spleen is responsible for removing older red blood cells from the body. As a result, these people may have a higher A1C % than expected.

It’s important to note here that A1C is not a perfect predictor of your risk of diabetes complications. It only predicts your complication risk if it accurately represents your average blood glucose. So, if there’s reason to believe that your A1C isn’t a good proxy for blood glucose, you and your healthcare team should not base your diabetes management plan on your A1C. Instead, your plan should be based on your CGM average or BG meter average (assuming you’ve collected enough blood glucose values at various times out throughout the day).

Bottom Line

Your average blood glucose is not really intended to predict your A1C. Rather, A1C is supposed to provide a way to estimate your average blood glucose over time.  Any A1C-based prediction may be off by as much as 20 to 25 mg/dL. For some people, it may make more sense to base diabetes treatment decisions off of their BG meter average than their laboratory-measured A1C.

best diabetes monitor - best diabetes blood glucometer

One Drop Guide to Type 2 Diabetes

But first: what is it even?

Type 2 diabetes (T2D), also known as diabetes mellitus type 2, is a type of diabetes in which glucose builds up in the bloodstream due to insulin resistance and low insulin levels. Insulin, which you can learn about here, is the hormone that regulates blood sugar.

But let’s dig a bit deeper, as far back as the ancient Egyptian pyramids. While most people refer to it today as T2D, diabetes mellitus type 2, as it’s scientifically recognized, has a very intriguing etymology. Egyptian manuscripts dating back to 1500 B.C (😱) record the symptoms of a deadly disease that caused frequent urination and unquenchable thirst. Around the same time, Indian physicians were seeing the same no-name killer. Victims’ urine attracted ants and flies, which eventually spurred those same physicians to coin the term madhumeha, or ‘honey urine.’

diabetes mellitus type 2

From madhumeha to mellitus

Fast forward (and move your maps 🗺) to Greece in the 1st Century AD. Greek physician Aretaeus of Cappadocia (others argue it was Apollonius of Memphis) coins the word diabetes, the Greek word for siphon (to pass through). Then, in 1978, British Surgeon-General John Rollo adds Latin term mellitus (“of or pertaining to honey”) to create the terminology as we know it today: diabetes mellitus (sweet siphon), type 1 and type 2.

Currently, there is no cure for type 2 diabetes. But you can manage type 2 diabetes well and avoid complications with a good diet, regular exercise, and, in most cases, some medication (e.g., metformin, insulin, etc.). Anyone can live a long and healthy life with T2D! The key is keeping blood glucose in range and sticking to a mindful, healthy lifestyle.

The Ultimate Guide to Type 2 Diabetes

In order to manage diabetes well, it’s important to understand exactly how diabetes works. That’s why we’ve created the One Drop Guide to T2D:

— to help you understand the basics of T2D, including the role of the pancreas and insulin

— to show you ways you can help your body achieve balance and lower your blood sugar levels


diabetes mellitus type 2

The One Drop Guide to Insulin 💉

One Drop Guide to Insulin


Everyone (everyone!) needs it to survive. For those of us living with diabetes, it is liquid gold. But why? What exactly is insulin?

When there’s an abundance of glucose in the bloodstream, the pancreas secretes insulin: a hormone produced by the beta cells, which live inside the islet cells, that live inside the pancreas. For every person on the planet, insulin is the key to getting glucose out of your blood and into your cells.

The Keys to Glucose Success 🔑

The insulin, once released, acts like a key (raise your hand if you, too, were given the lock & key analogy upon diagnosis! 🙋‍♀️🙋‍♂️): it opens the door to cells throughout the body so that the cells can take in the glucose (the sugar) and use it later as an energy source.

But where is all this glucose coming from? We need it for energy, but how do we get the glucose, the energy, in the first place? FOOD. Quite literally, just about anything we put into our mouths is broken down into energy. What we don’t use immediately as an energy source, we store in cells throughout the body for later use. That energy storage is only possible through… you guessed it! Insulin.

When the Keys Don’t Fit 🔒

None of this works properly (the locks, the keys, the energy storage) when you’ve got diabetes. Having diabetes means your body can’t make insulin and/or use it properly. Either insulin is not produced at all, or cells in the body have difficulty absorbing insulin. Without insulin production or absorption, glucose can’t properly be stored in bodily cells. Instead, the glucose remains in the bloodstream and glucose levels start to rise. While we need glucose to live, too much of it can be a very bad thing. To the point of death. ☠

Insulin: A Brief History

The discovery of injected animal insulin in 1922 to stabilize blood glucose levels was the ultimate game-changer. And using breakthrough rDNA (recombinant DNA) technology in 1973, scientists produced synthetic (human) insulin. It’s these synthetic (both human and analog) insulins that we use today to keep blood sugars stable.

The Ultimate Guide to Insulins

Thanks to human and analog insulins, we now have a plethora of options available when it comes to blood glucose management. There are lots of different types of insulin used to treat diabetes. But how are they different? What do they do? And how exactly do they work?

Check out the One Drop Guide to Insulin [PDF version here] to learn the answers to these questions and feel more empowered and informed about your diabetes. It covers all the basics: how insulin lowers blood glucose, how it relates to diabetes, and onset, peak, and duration data for 19 popular brands: Afrezza, Apidra, Humalog, Novolog, Humulin R, Novolin R, Humulin N, Novolin N, Lantus, Toujeo, Basaglar, Levemir, Tresiba, Humalog Mix 75/25, Humalog Mix 50/50, Novolog Mix 70/30, Humulin 70/30, Novolin 70/30, and Ryzodeg 70/30.

After you’re done, check out the One Drop Guide to A1C to learn everything you need to know about this core diabetes metric.




Low carb breakfast recipe

Staying Low-Carb for Spring Holidays

easter 2018 / passover 2018 - diabetes friendly recipes

Spring is in the air! 🌷 April is just around the corner. With it comes warmer weather, sunshine, & festivities! Easily navigate Passover and Easter with these tips & festive low-carb recipes.

Passover 2018

Friday, March 30 – Saturday, April 7

A ceremonial dinner (Seder) of symbolic foods marks the beginning of Passover. The shared Seder plate is a mix of high- and low-carb bites.

High Carb ⬆

Matzo (unleavened bread) 23g carbs, per piece

Charoset (fruit, nut & wine paste) 21.5g carbs, per 1/4 cup

Karpas (potato) 30g carbs OR (parsley) 0.2g carbs

Low Carb ⬇

Maror (horseradish) 1.7g carbs, per 1 tbsp

Chazeret (romaine lettuce) 0.9g carbs, per leaf

Zeroa (lamb shank) 0g carbs, per 1 oz

spring holidays, low-carb

Seder Plate Tips:

  1. Opt for whole grain matzo, which has slightly fewer carbs (19g) and more fiber.
  2. Avoid adding sugar or honey to the Charoset. Instead, use a Kosher sweetener like stevia.
  3. Sip on a dry red wine (~4g carbs per 8 oz).

For the remaining meals, the Jewish people give up “the five species of grains”– wheat, rye, oats, barley, and spelt. With these high-carb ingredients off limits, plenty of Passover recipes are Kosher and diabetes friendly 😊


Side Dishes

Transition from starchier, high-carb winter vegetables and take advantage of lighter, spring veggies. Greens, asparagus, and Brussels sprouts are all awesome low-carb options. Avoid kugels and other potato-based dishes. Instead, consider making a frittata or a zucchini-based casserole.

Main Courses


Enjoy these dairy-free and diabetes-friendly desserts. Your friends and family won’t believe they are low-carb and you won’t be left feeling deprived!

Easter 2018

Sunday, April 1

April Fool’s! Nope, no jokes here — Easter falls on the same day as April Fool’s this year. There are sure to be lots of eggcellent jokes to be had this Easter 2018. 😝

Other than April Fool’s, though, Easter means new beginnings, family… and chocolate 🍫 ! It’s hard to stay on track when the grocery isles are lined with Cadbury Eggs, jelly beans, and marshmallow Peeps. But with a little preparation and creativity, you can stay on track and enjoy the holiday season.

spring holidays, low-carb

Low-Carb Kids

A diabetes diagnosis doesn’t mean your child has to miss out on Easter! Pack diabetes-friendly Easter baskets with small gifts instead of sugary treats. Stickers, small stuffed animals, bubbles, and chalk are all fun substitutions. Limit sweets to a few pieces of dark chocolate or sugar-free candy. Keep your child entertained with coloring pages, spring time crafts, and egg dying.

Sweet Moderation: Sugar-free candy may have less impact on blood glucose but be aware that the sugar alcohols (used as sweeteners) can cause digestive distress.

Low-Carb Brunch

Spend time with your friends and family while munching on these delicious low-carb options. Don’t forget dessert!


Meat & Fish



Hoppy eating 🐰 !


Diabetes & Eye Care: Keep Your Vision Sharp

We’ve had huge advancements in eye care.

Thanks to new diabetes medications and devices, it has become easier than ever to improve our diabetes control and reduce the chances of developing severe eye complications.

Additionally, new cutting edge eye tests and treatments have played a major role in the decrease of diabetes retinopathy.

So much so, that the American Diabetes Association has published its first position statement on the subject in 15 years. The position statement recognizes that “diabetic retinopathy diagnostic assessment and treatment options have improved dramatically”. It also emphasizes the importance of controlling glucose, blood pressure, and lipid levels to minimize the risk of developing diabetic retinopathy and of reducing its progression.

It’s easy to keep an eye on your eyes. Here’s how to make eye care a part of your daily routine.

6 tips to help you keep your eyes healthy and avoid complications related to diabetes.  

1. Schedule regular checkups.

Make an appointment with your eye doctor at least once a year. It is much easier to find and treat problems early with regular monitoring. Regular tests like dilating the pupil will help your doctor view the blood vessels in your eye and check for damage. Also, talk to your doctor about eye care specific to your needs – contacts lenses, eye drops, glasses, etc.

2. Check blood sugars often.

Maintaining your blood glucoses will help prevent damage to the tiny blood vessels in your eyes. An A1c test can help you gauge what your average blood glucose is; aim for 7️⃣% or below.

3. Manage your blood pressure.

High blood pressure alone can cause eye problems. If you have high blood pressure ⬆️↗️ and diabetes, talk to your doctor about ways to reduce your blood pressure (medication, diet, exercise). Also be sure to have your blood pressure checked regularly. For most people, it should be 140/80 or lower.

4. Check your cholesterol levels.

Get your cholesterol checked regularly. High levels of “bad” LDL are linked to blood vessel damage. Boost “good” HDL cholesterol by eating heart healthy foods, cutting out trans fats and exercising regularly. Talk to your doctor about ways you can better control your cholesterol levels. ❤️

5. Get moving.

Exercise helps you control your blood glucose, shed pounds and manage your blood pressure. ‍Talk to your doctor about a workout plan that is best for you.

6. Taste the rainbow.

A healthy diet filled with colorful foods will help you maintain or lose weight, reduce blood pressure and provide your body with essential nutrients and vitamins. Try to incorporate dark leafy greens, organic eggs (especially the yolks), fatty fish like salmon, fruits high in vitamin C and almonds into your diet. Avoid excessive carbs, this can result in high insulin levels and can disturb eyeball growth.

Quick and Easy Snacks (10 Carbs or Less!)

low carb snacks

Truth: low carb snacks are some of the tastiest and most filling out there. Science shows that gram for gram, protein and fat tend to be more filling than carbohydrates. And don’t forget about fiber-rich veggies! They also keep your tummy happy for longer, because they digest slower than refined carbohydrates like pasta or white rice.

This comes as no surprise to us — we love our tasty low-carb foods! (And we know all about choosing carbs wisely to avoid big blood sugar spikes 😉)

Check out our list of quick and delicious low carb snacks that will fill you up and keep your blood sugar down.

10 Tasty Low Carb Snacks

Avocado, cheese, deli meat, eggs, lox, olives, peanut butter, pickles, and yogurt — eat up! (Did we mention they’re all under 10 carbs per serving!?)

low carb snacks

low carb snacks

low carb snacks

low carb snacks

low carb snacks

low carb snacks

low carb snacks

low carb snacks

low carb snacks

low carb snacks

Want to learn more about staying low carb? Check out our One Drop Guide to Carbohydrates!