Getting Started with Low-Carb for Type 1 Diabetes: A Practical Guide

Before You Start

This guide assumes you've already decided to try low-carb. If you're still exploring whether this is right for you, start with Can Type 1s Achieve Stable, Near-Normal Blood Sugar?

You must work with a qualified healthcare professional who understands very low-carbohydrate diets. Your insulin needs will change dramatically—often within hours. Without proper medical supervision, you risk dangerous hypoglycemia.

Read the complete Safety Warnings: Starting Keto with Diabetes Medications before making any changes.

---

What You're Committing To

Ketogenic diet for Type 1 diabetes:

• Typically 20-50 grams carbs per day (your healthcare provider should help determine your specific target)
• Moderate protein (1.0-1.5g per kg body weight)
• Enough fat to feel satisfied (not necessarily "high fat")

You'll eat: Meat, fish, eggs, cheese, butter, cream, non-starchy vegetables, nuts (moderate), berries (small amounts)

You'll skip: Bread, pasta, rice, potatoes, most fruits, sugar, processed foods

See What to Eat on a Ketogenic Diet for meal ideas.

How Your Insulin Needs Will Change

Studies show total insulin reductions of 30-70%:

• Basal insulin typically drops 30-50%
• Bolus insulin drops 50-75% or more
• One 10-year study showed 43% reduction
• A 2023 study showed 70% reduction

Why? Less carbs means less glucose entering your bloodstream. You need far less insulin to manage it.

Critical: Reduce insulin before you reduce carbs, not after.

Two Ways to Start

Option 1: Immediate (20-50g carbs from day 1)

• Faster adaptation and results
• Requires aggressive insulin reduction immediately
• Best if you can monitor very closely

Initial adjustment:

• Studies show initial basal reductions typically range from 40-50%, but your healthcare provider must determine your specific adjustment
• Significantly reduce bolus (see mealtime strategy below)

Option 2: Gradual (reduce 25-50g weekly)

• Easier to fine-tune adjustments
• Less dramatic adaptation
• Takes longer to see full benefits

The gradual approach:

This works exactly like the carb counting your healthcare team already taught you—just with fewer carbs each week. As you reduce carbohydrates gradually, you'll reduce insulin accordingly using the same assessment skills you normally use.

• Bolus insulin: Calculate for each meal based on actual carbs eaten, just as your healthcare team taught you. As carbs decrease, so will your bolus needs—naturally and gradually.
• Basal insulin: Reduce gradually as your overall carb intake decreases. How much depends on how quickly you reduce carbs. Work with your healthcare provider to adjust based on your patterns.
• The golden rule: It's safer to give slightly too little insulin and correct afterward than to risk lows. Better to see a gentle rise and take a small correction than to over-dose.

If you use a CGM: Your overnight blood sugar should ideally show a flat line (not counting dawn phenomenon effects). If you see a slow rise or fall overnight, your basal needs adjustment.

Important considerations for overnight readings:

• Late meals affect overnight patterns. Protein and fat absorb slowly over 3-4+ hours. Try to eat your last meal at least 4 hours before bed (especially while tuning in your doses), so you can correct if needed before sleep. This allows for a more predictable flat curve overnight.
• Don't aim too low initially. Don't target 5 mmol/L (90 mg/dL) in the beginning. Aim a bit higher for safety reasons while you're learning your patterns.
• Remember: stable first, then gradually aim lower. Get consistent, predictable readings before working toward tighter ranges.
• Confirm your target range with your healthcare team.

Choose based on your comfort level and your healthcare team's recommendation.

Understanding Protein and Fat

If you've been focused primarily on carb counting, you're about to discover something many Type 1s don't realize: protein also raises blood sugar—just much more slowly and gently.

The rough guideline: 20 grams of protein affects blood sugar similarly to about 10 grams of carbs. But instead of spiking in 30-60 minutes, protein's effect unfolds over 2-4 hours or longer.

This is actually good news. The slow, gentle rise gives you plenty of time to see it coming and respond. Many people check their blood sugar 2-4 hours after meals and take a small correction if needed—typically just 1-2 units.

The type of protein matters too. You'll likely notice differences:

• A good ribeye steak? Minimal blood sugar effect for many people
• Ground meat or processed meats? Often absorb faster and need slightly more insulin
• Fish, chicken, eggs? Somewhere in between

Fat slows everything down even more, which is why a fatty meal might show its full effect 3-4 hours later.

Take notes during your first few weeks. Your body's response is individual. What works for someone else might not match your experience exactly.

The learning curve feels manageable because everything happens gradually. You're not chasing rapid spikes anymore. You're making small adjustments to gentle, predictable trends. Most people find this far easier than trying to match fast-acting insulin to rapidly absorbed carbs.

---

Your Mealtime Insulin Strategy

The safest approach for beginners

Your healthcare provider should help you develop your specific strategy. Many people start with this approach:

1. Before the meal: Take only correction insulin if blood sugar is high (aiming for low-normal range), and avoid meal insulin initially.

2. After the meal: Check blood sugar after 1-2 hours. If it starts climbing, take a small dose of insulin.

3. Monitor closely for the next 2-3 hours. Take another small dose if needed.

4. Keep detailed notes. Track exactly what you ate, when you took insulin, doses, and blood sugar readings. Use the Glysimi app or a detailed logbook.

As you gain experience (after 1-2 weeks), you'll learn:

• How much insulin to take with the meal
• How much to take 2-3 hours later
• Which foods need more or less insulin
• Your personal timing patterns

Why this works: The slow, predictable rise from protein is forgiving. Better to under-dose and correct than over-dose and fight lows.

The First Week: Intensive Learning

Day 1-2

• Test blood sugar every 2-3 hours
• Keep glucose tablets handy (as always)
• Start testing ketones
• Increase salt intake significantly (add to food, drink broth)
• Stay well-hydrated

Day 3-7

• Continue frequent testing (every 3-4 hours)
• Test ketones daily
• Watch for "keto flu" (headache, fatigue, irritability)
• Take detailed notes on everything: food, timing, doses, readings, how you feel
• Blood sugar patterns should start becoming more predictable
• Hunger typically decreases significantly

Expected ketone levels: 0.5-3.0 mmol/L is perfect. Higher levels (3-5 mmol/L) can occur with extended fasting (24+ hours) but are unusual on a regular keto diet.

---

Understanding Ketones: Safe vs. Dangerous

Nutritional Ketosis (Safe)

• Ketones: 0.5-3.0 mmol/L (occasionally 3-5 mmol/L with prolonged fasting)
• Blood sugar: Normal to low-normal
• How you feel: Good energy, mental clarity
• What it means: Your body is efficiently burning fat for fuel

Diabetic Ketoacidosis (Emergency)

• Ketones: >5 mmol/L (often >15 mmol/L)
• Blood sugar: Usually very high (>13 mmol/L or >250 mg/dL), but not always
• Symptoms: Nausea, vomiting, fruity breath, confusion, rapid breathing
• Action: Seek immediate medical attention

Key difference: Ketoacidosis (DKA) happens with insufficient insulin. Nutritional ketosis happens with adequate insulin while eating very low carb.

When to call your doctor immediately:

• Ketones >5 mmol/L with high blood sugar
• Ketones >3 mmol/L with symptoms (nausea, vomiting, confusion)
• Any DKA symptoms

---

Managing "Keto Flu" (Days 3-7)

Common symptoms: Headache, fatigue, irritability, muscle cramps, dizziness

Why it happens: Your body is adapting and shedding water/electrolytes

How to minimize it

1. Increase salt significantly - add to food, drink broth (3-5g extra sodium daily)
2. Stay hydrated - but don't overdo plain water
3. Consider magnesium (300-400mg) and potassium (from food)
4. Eat enough fat - don't restrict calories while adapting
5. Be patient - symptoms typically resolve within a week

Most people feel dramatically better after the first week, with improved energy and mental clarity.

---

Adjusting Your Basal Insulin

Why it changes: Less glucose from food, improved insulin sensitivity, less compensation needed

How to adjust:

1. Research suggests initial reductions often fall in the 30-40% range, but work with your healthcare provider to determine your specific starting point
2. Test fasting blood sugar each morning
3. Test overnight for the first week
4. Your healthcare provider may recommend small adjustments (often 1-2 units) every few days based on your patterns
5. Look for stable overnight and pre-meal readings

For pump users: You may need different adjustments for different times of day. Dawn phenomenon often reduces significantly for many people.

Common Issues and Solutions

Blood sugar too low frequently:

• Work with your healthcare provider to reduce basal (often by 1-2 units)
• Reduce or delay bolus doses
• Ensure you're eating enough

Blood sugar spiking after meals:

• Check for hidden carbs in foods
• Weigh portions to verify protein amounts
• Gradually increase mealtime insulin
• Consider delayed second dose for protein

Exercise Adjustments

What changes: Exercise affects blood sugar far less dramatically on keto. You're burning fat for fuel, so glucose doesn't deplete as rapidly.

General approach

• Light activity (walking): Usually no adjustment needed
• Moderate activity: Some people need 20-30% less insulin before/during—your healthcare provider can help you determine your adjustments
• Intense activity: May cause brief spike (stress hormones), followed by enhanced insulin sensitivity

Learn your patterns: Test before, during (if possible), and after exercise. Adjust gradually based on your data.

What Success Looks Like

You'll know this is working when:

• Blood Sugar becomes highly predictable
• Time-in-Range improves to 80-90%+ (many achieve 90%+)
• Insulin needs stay 30-60% lower
• Hypoglycemia becomes rare and gentle
• HbA1c drops to <6.0% or even <5.7%
• Hunger and cravings disappear
• Energy and mental clarity improve dramatically

Studies show average HbA1c improvements of 1-2%, with many achieving near-normal (non-diabetic) levels.

---

Critical Reminders

Most important:

1. Medical supervision is essential - not optional
2. Take detailed notes - especially the first 2-4 weeks (use the Glysimi App)
3. Start conservatively with insulin - under-dose and correct rather than over-dose
4. Monitor frequently - especially first week
5. Be patient - adaptation takes 2-4 weeks
6. This is about glucose control, not necessarily weight loss

When to contact your healthcare provider immediately:

• Ketones >5 mmol/L with high blood sugar
• Ketoacidosis symptoms (nausea, vomiting, confusion, rapid breathing)
• Severe Hypoglycemia not responding to treatment
• Any time you feel seriously unwell

---

Next Steps

1. Schedule appointment with healthcare provider
2. Review safety warnings again: Important Safety Information
3. Stock your kitchen: What to Eat on a Ketogenic Diet
4. Get supplies: Test strips, ketone testing, detailed tracking system (Glysimi App)
5. Start on a day you can monitor closely

The research shows this works. Studies document 80-97% time-in-range and HbA1c approaching non-diabetic levels. Hundreds of case studies and thousands of personal experiences confirm it.

The question is: are you ready to see what stable blood sugar feels like?

---