EP049: The Insulin Playbook
The Insulin Playbook: Simple Rules To Dose Smarter, Feel Better, and Take Control
“Insulin has two jobs—basal for background, bolus for food. Get those right, and everything changes.”
This is your plain‑English Insulin Playbook. If you use insulin—or love someone who does—this will help you dose with confidence. We’ll skip “what is insulin” and go straight to how it really works, why two types matter, and the simple math that turns guessing into a plan. We’ll keep it friendly, clear, and at a fifth‑grade reading level. Use this as education. Always talk to your doctor before making changes
The Two Jobs of Insulin
Insulin has two jobs. Knowing the difference changes everything.
Job 1: Basal (background) insulin
Think “basic,” “background,” or “baseline.”
Works all day and all night.
Keeps blood sugar steady when you’re not eating (sleep, between meals).
Helps “pump the brakes” on the liver, which releases glucose even when you don’t eat.
Job 2: Bolus (mealtime and corrections)
Think “bowl” of food—bolus covers what you eat.
Covers carbs at meals.
Can also lower a high number before a meal (correction).
Simple way to remember:
Basal manages the glucose your body makes.
Bolus manages the glucose from food (and does corrections).
Why Your Fasting Can Look “Fine,” But A1C Is Still High
Your liver makes glucose around the clock to fuel your brain and organs. Insulin tells the liver to slow down. Without enough basal insulin, the liver keeps “dumping” sugar—yes, even at 3 a.m.
What often goes wrong:
People keep raising basal insulin to “fix” high A1C.
Fasting looks good, but after‑meal spikes are huge.
This is called over‑basalization.
Red flags for over‑basalization:
Fasting looks near target (for example, 90–130), but A1C stays high.
Basal dose is over 0.5 units per kilogram and A1C is still high.
Big spikes after meals, but no mealtime plan or carb ratio.
Why Sliding Scale Keeps You Chasing Highs
Sliding scale is reactive. It only looks at your current number. It ignores:
What you ate
Your Total Daily Insulin (TDI)
Your own insulin sensitivity
Result: You’re always a step behind. Better: use proactive rules based on your TDI.
The Master Number: Total Daily Insulin (TDI)
Everything starts with your Total Daily Insulin (also called TDD). It is:
The sum of all units you take in 24 hours
Basal + bolus + corrections
Why TDI matters:
It drives your correction factor (how much 1 unit lowers sugar)
It drives your carb ratio (how many carbs 1 unit covers)
It helps balance basal vs. bolus (many do best near a 50/50 split)
Your Starting Point: Weight‑Based Dosing (General Education)
Many plans start with weight:
Insulin sensitive: about 0.3 units/kg/day
Typical: about 0.4–0.6 units/kg/day
Insulin resistant: about 0.6–1.0 units/kg/day
Severe resistance: can be >1.0 units/kg/day
Note: Your provider chooses and adjusts this with you. Never adjust on your own.
The Insulin Calculator Rules (The Helpful Math)
These common rules help your team personalize dosing. They use your TDI.
The 1700 Rule (Correction Factor / Insulin Sensitivity Factor)
Tells how much 1 unit of rapid‑acting insulin lowers your blood sugar.
Formula: 1700 ÷ TDI
Example: TDI = 50 → 1700 ÷ 50 = 34
One unit lowers about 34 mg/dL.
The 450 Rule (Carb Ratio)
Tells how many grams of carbs are covered by 1 unit of rapid‑acting insulin.
Formula: 450 ÷ TDI
Example: TDI = 60 → 450 ÷ 60 = 7.5
One unit covers about 7.5 grams of carbs.
The 1500 Rule (For “Regular” insulin)
Used when dosing Regular (R) insulin (older, slower), not rapid analogs.
Formula: 1500 ÷ TDI
How It Works Together (Simple Scenario)
You plan to eat 45 grams of carbs.
Your carb ratio is 1 unit per 7.5 grams → 45 ÷ 7.5 = 6 units for the meal.
Your current glucose is 200. Your target is 120. Difference = 80.
Your correction factor is 34 mg/dL per unit → 80 ÷ 34 ≈ 2.4 → round down to 2 units.
Total bolus = 6 (meal) + 2 (correction) = 8 units.
Important:
Rapid‑acting insulin timing matters. Many need to dose 10–20 minutes before eating (ultra‑rapids may be closer to meal time). Follow your provider’s guidance.
Finding The Balance: Basal vs. Bolus
Many people do best when their total insulin is close to:
About 50% basal and 50% bolus
Or within 45/55 either way
If your basal does all the work, you risk lows when meals are small, and highs after bigger meals. If bolus is ignored, A1C stays up from meal spikes.
Common Signs Your Plan Needs a Tune‑Up
Fasting looks okay, but A1C is high → likely over‑basalized; you may need mealtime coverage.
Doses keep going up, but A1C won’t budge → timing or meal plan may be off.
Big spikes after meals and no one discussed a carb ratio → ask your provider.
Same mealtime dose no matter what you eat → ask about carb ratios.
Always “chasing” highs with sliding scale → ask about proactive dosing (carb ratio + correction factor).
Insulin Resistance Explained (Why Doses Climb)
Insulin resistance is like “fog on the runway.” Your body needs a stronger signal.
The liver keeps making glucose even when you aren’t eating.
If you only raise basal, meals still spike—and you can crash when meals are smaller.
Good news: Insulin resistance can improve. Weight loss (especially around the middle), more movement, better sleep, stress care, and building muscle can lower insulin needs over time.
Tools and Tech: Injections vs. Pumps
Injections:
Basal once daily (or as prescribed).
Bolus before meals.
Pumps and Automated Insulin Delivery:
Deliver tiny, precise doses all day (no separate long‑acting).
Can lower TDI because delivery is efficient.
Some systems can automate parts of the math once set up correctly.
Cost and Real‑World Options
If cost is a barrier, ask about:
Patient assistance programs
Lower‑cost options at Walmart (Regular “R” and NPH “N” insulin)
Regular (R): slower start; often dosed ~30 minutes before meals
NPH (N): intermediate; has a peak; timing and meals matter
Important: Dosing and timing are different. Always get guidance from your care team.
Samples are less common now. Plan ahead with your clinic.
Food Notes Without Food Fights
You don’t have to avoid all carbs.
Balanced meals, fiber, and portion awareness help a lot.
Carb ratios allow flexibility at meals.
A registered dietitian can help you “eyeball” carbs and plan simply.
Your 3‑Day Challenge
Add up your Total Daily Insulin (TDI) each day for 3 days.
Include basal, bolus, and corrections.
Bring your average TDI to your next appointment.
Ask your provider:
What is my correction factor (1700 ÷ TDI)?
What is my carb ratio (450 ÷ TDI)?
Do I look over‑basalized?
Should we personalize my sliding scale or switch to carb ratio + CF?
Would a pump or automated system help me?
Key Takeaways
Basal controls background glucose; bolus covers food and corrections.
Know your TDI. It powers your Insulin Calculator rules.
If fasting looks fine but A1C is high, you may be over‑basalized.
Sliding scales are reactive; carb ratios and correction factors are proactive.
Improving insulin sensitivity can reduce insulin needs over time.
If you found this helpful, share it with someone who uses insulin, or anyone trying to avoid insulin by acting early. If you have type 1 and struggle to explain the work you do each day, send this to your family—it shows the reason behind the math.
Need support? Reach out to your diabetes care team, or connect with a certified diabetes care and education specialist or registered dietitian to make this simpler in your daily life.
Take courage! You can do this—and we can help.
Disclaimer
The information in this blog post and podcast is for educational and informational purposes only. It is not medical advice, diagnosis, or treatment, and it does not replace a one-on-one relationship with your physician or qualified healthcare professional. Always talk with your doctor, pharmacist, or care team before starting, stopping, or changing any medication, supplement, exercise plan, or nutrition plan—especially if you have diabetes, prediabetes, heart, liver, or kidney conditions, or take prescription drugs like metformin or insulin.
Results vary from person to person. Examples, statistics, or studies are shared to educate, not to promise outcomes. Any discussion of medications, dosing, or side effects is general in nature and may not be appropriate for your specific situation. Do not ignore professional medical advice or delay seeking it because of something you read or heard here. If you think you are experiencing an emergency or severe side effects (such as persistent vomiting, severe diarrhea, signs of dehydration, allergic reaction, or symptoms of lactic acidosis), call your local emergency number or seek urgent care right away.
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