Boluses basals and corrections Getting the doses right

Boluses, basals and corrections – Getting the doses right Stephen W. Ponder MD, FAAP, CDE Scott & White Clinic Temple, Round Rock and College Station

Generally speaking, diabetes self care is the result of the “perfect” minus the “reality”. We can (at best) only control our “reality”. Perfection in diabetes self care is not possible. Therefore, we must try to accept the size of the gap. Gaps shrink and expand. So…by this thinking… are you OK with the current size of your “gap”? Perfection (not possible) - Reality (what IS possible) = The diabetes care “Gap”

Ponder’s Pumping Principles I. An insulin pump is no better or worse than the human being attached to it VII. Quality diabetes self-care is more about the PROCESS than it is about OUTCOMES II. Master carb counting well BEFORE pumping VIII. Technology changes; people don’t III. Age is not a limiting factor for a pump IX. Self-consistency is a virtue IV. Garbage in, garbage out: beware of the “pump and dump” phenomenon V. The best pump doctor acts as a coach VI. Simple is a good place to start, but pumping skills MUST advance over time X. Everyone’s blood sugar fluxes; seek out patterns in the chaos XI. Success is always a relative thing XII. Don’t ever be afraid to start over

Why should I care about after meal blood sugar levels?

Postmeal Blood sugars, A 1 c and CV Risk Vascular system 220 glucose 180 Hb. A 1 c 8% 140 7% 100 6% 5% Pre-meal 95 2 hr ? Pre-meal 115 Goal: improve post-meal control: BG < 180 mg/dl

Before meal sugar After meal sugar

5 cardinal concepts to understand 1) 2) 3) 4) 5) Target (range) Basal rate(s) Insulin: CHO ratio(s) Correction factor(s) Insulin on board (IOB) • • • A number or range Start with 1 rate Start with 1 I: CHO Start with 1 CF 3. 5 to 5 hours (4)

Diabetes is best approached 1 day at a time

Diabetes care is a process, not an action • It has purpose, meaning or direction • It has a logical structure or order • Steps are mostly measureable • It has a goal, outcome or result

Duration Of Carb Action Or…UNDERSTAND YOUR TARGETS • Most carbs have most of their affect within 1 to 2. 5 hours • But complex carbs are slowed down by their protein and fat content

Carb Counting • Accounts for half the day’s control • Accuracy allows boluses to match carbs for post-meal control and a significantly lower A 1 c • Made easier with automatic carb bolus calculations by pump • Always make an effort to estimate (if not count carbs)

D-teens count carbs POORLY 23%

TIP: A standing insulin dose (or regimen) is ALWAYS CHANGED LAST • When troubleshooting a type 1 diabetes blood sugar problem • First consider… – Food – Timing – Equipment • BEFORE changing an insulin regimen

Why is the TDD so important? ½ TDD/24 = basal rate Insulin on Board (IOB) (2 -8 hours) 500/TDD = carb ratio Total Daily Dose (TDD) TARGET BG 1800/TDD = correction

Average TDD insulin ranges by age and weight 0. 6 -0. 8 U/kg/d (toddler) 0. 8 -1. 0 U/kg/d (child) 1. 0 -1. 2 U/kg/d (teen)

Basal-Bolus: Example Calculations 30 units as glargine Give dose at bedtime TDD 60 units ~ 30 units divided as boluses 10 – 10 + snacks OR… 60 units 500 rule 8. 3 ~ 10 Insulin to carbohydrate ratio 60 units 1800 rule 30 Correction factor (aka sensitivity factor)

Adjust The TDD For A High Avg. BG or A 1 C Example: someone with a TDD of 35 units and few lows. A 1 c = 9%, so more insulin is needed: about 3. 2 units.

worksheet

J. F. 8/7/89 7/6/01 8. 0 49. 7 7 H 14 N 5 H 9 Lantus 35 26 13 35 35 26. 25 13 1. 08 1. 0 Novolog 26 26 69. 2 19 100 -150 75 1: 20 100 -150 7/7/01

What is basal insulin? Maintains balance Minimizes drift/flux +/- 30 mg/dl over time Does not account for disruptive effect of snacks, activity or stress • May change over time • Usually 40 -60% of TDD • •

What defines an effective basal insulin? (here’s a good visual)

Hints about basal insulin • 50% Rule: basals usually make up 40 to 60% of an accurate Total Daily Dose • Basal rates will be similar through the day, such as between 0. 45 and 0. 7, or between 1. 0 and 1. 4 • Adjust a basal rate in small steps – 0. 05 to 0. 1 u/hr • Change basals 3 to 8 hours before need arises

Starting a basal rate Example: Pre-pump TDD = 48 units 75% of 48 units = 36 units 50% of 36 units = 18 units 18 divided into 24 hours = 0. 75 U/hr B A S A L time

Basal rates 3 AM Midnight 6 AM Programmed for the “typical” day 1. 0 U/hr 0. 75 U/hr B A S A L time 0. 5 U/hr

% Survey: number of basal rates used www. insulin- N = 816 pumpers. org

Breakfast 6 – 9 AM 2 - 4 AM Snack Lunch b Supper s u l bo s u l o Snack Breakfast s u l bo ~2 AM - 4 AM is the physiologic nadir for insulin ~ 40% of hypoglycemia occurs during sleep! Often asymptomatic!

Can’t “target practice” without a target! • Targets are specific numbers • May vary based on time of day or other considerations • Are mathematical guides only • Must be reasonably set

“Practice approaches perfect”

Selecting a blood sugar target ü ü ü Upper and lower limits (range) A specific number Individualized Achievable Adjustable 100 mg/ ddll 120 140 mg/dl / mg 0 3 1

Set your BG range reasonable 100 -200 80 -180 70 -150 individualized

Two week pumper log sheet (complete the open spots) Influenced by basal Checks overnight basal(s) Influenced by boluses

What defines a correction? • Correction: to bring something back into order or balance • Diabetes: to lower (or raise) and out of range blood sugar level. • Situational variables – Time – Quantity – Recent/impending actions • Reproducibility? • Evolving nature? Stock “correction”

Example: 1 to 25 “Correction” dose 250 . . . 5 . 110 mg/dl 180 mg/dl . . bolu s gluco se . . 250 – 125 / 25 = 55 . mg/dl . Actual – target / 25 2 hours 80 mg/dl “Acceptable” = “target” +/- 30 mg/dl 0. 75 U/hr B A S A L time I N S U L I N

What defines a meal dose? Tight coverage by insulin for changes in blood sugar in non-diabetic people • “Covers” the potential rise in sugar level after eating a meal. • In non-D people, the 2 hour after meal BG is <140 mg/dl (by definition) • Personal goals must be set by the patient/doc

Insulin to carb ratio • Based on the “ 500 Rule” • 500 ÷ TDD = grams of carbs covered by 1 unit insulin • Example: 500 ÷ 60 = 8. 3 = ~ 8 • Therefore: 1 unit for every 8 grams • Easier: 1 unit for 7. 5 gm or 2 for 15 grams • 15 grams = 1 carbohydrate choice CH O I G Blood sugar level

Example: 1 to 10 Insulin to Carb [I : CHO] ratio 60 / 10 = 66 CH O . 60 grams CHO / 10 . . . 125 mg/dl 6 bolu s gluco se . . . 2 hours 0. 75 U/hr B A S A L time 150 mg/ dl . . . 180 mg/dl . . 80 mg/dl “Acceptable” = “target” +/- 30 mg/dl I N S U L I N

Carb Ratio or Factor • Carb factor – how many grams of carb are covered by 1 unit insulin • Carb bolus is based on: • Your carb factor • How many grams of carbs you plan to eat • Your BG allows a correction bolus determination • Amount of BOB (IOB) still active (ALSO determined from BG!) • A pump can determine the bolus needed for a meal when the carb count and the carb factor are accurate • Visit your dietitian to learn!

Check Your Carb Boluses • Does your carb factor work for LARGE meals? – half your weight (lbs) as grams of carb • Are carb counts accurate? • Are boluses given 20 min before meals when the glucose is normal? For frequent lows after meals –> raise carb factor # For frequent highs after meals –> lower carb factor #

An Accurate Carb Ratio or Factor: • Returns the blood sugar: ü to within 30 mg/dl (1. 7 mmol) of where it started ü by the time selected for your duration of insulin action (DIA) ü with no lows within 5 hours after carb bolus given

Carb Bolus Varieties n Normal carb bolus n n Extended or square wave bolus n n Bolus taken immediately – most meals Bolus extended over time – gastroparesis, pizza Combo or dual wave bolus n Some now, some later – bean burritos, al dente pastas and pizzas, Symlin

Unused insulin “Stacking 6 Units effect” 7 Units 6 Units 4 -6 hours 0. 75 U/hr B A S A L time

Avoid Insulin Stacking • The goal is to help patients prevent over-correcting • Available scientific data says how much active insulin remains • Current practices to avoid insulin “stacking” include: • Crude formulas (ie. 25% per hour or 50% of usual) • Crude strategies (ie. set a high Post-Prandial target BG)

“Thinking like a pancreas” example 220 mg/dl 2 units 5 units 7 units Does blood sugar (yes or no) 1 to 50 T = 120 Correction or sensitivity factor, includes target blood sugar (yes or no) 75 gm Carbs to be eaten (limited by ability to count carbs effectively) (counts, guesses, or doesn’t count at all) 1 to 15 Insulin to carb ratio (uses or doesn’t use) Insulin dose (given by doc, guessed, or calculated)

Bolus Size (Relative To Wt) Affects The DIA Measured as units per kg(2. 2 lb) How long a bolus will lower the BG: 4 hrs • Larger boluses have a longer duration of action. • For 50 kg (110 lb) person: – 0. 3 u/kg = 15 u – 15 u/kg = 7. 5 u – 0. 075 u/kg = 3. 75 u Becker et al. Diabetes. 2005; 54 (Suppl. 1): 1367 P

Recommendations For DIA Times • DIAs on current pumps can be set from 2 to 8 hours. An inaccurate DIA can significantly impact control. Mudaliar et al: Diabetes Care, 22: 1501, 1999

Basal/Bolus Balance < 50% Basal Duration < 5 yrs Thin Physically active High carb/low fat diet ~ 50% Basal > 50% Basal Most people Duration > 5 yrs Puberty Less active Insulin resistant Low carb diet

Stop Lows First Better control and more stability • Mild lows cause followup lows • Small epinephrine release makes muscles sensitive to insulin • Can lead to another low as much as 36 hours after the first • More carbs than usual are needed Severe lows cause highs Higher stress hormone release makes glucose rise for 6 -10 hrs Excess carb intake leads to highs Boluses may be reduced/skipped More insulin than usual needed To stop lows, lower the TDD!!!

Benefits Of Frequent checking 400 (22) 300 (17) 1 test versus 7 tests a day 200 (11) 100 (5. 6) Breakfast Lunch Dinner Bed

Actual A 1 c Versus Testing Frequency Data From 378 People On Pumps Atlanta Diabetes Associates study: 378 patients sorted from a database of 591 Pumps=MM 511 or earlier BG Target=100 C peptide <0. 1 ADA: < 7%% Hb. A 1 c=5. 99+5. 32 / (BGpd+1. 39) AACE: < 6. 5% P. Davidson et al: Diabetes 53 (suppl 2): abstract 430 -P, 2004

Questions?