Why sglt 2 inhibitors are contraindicated in t1dm
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SGLT2 inhibitors type 1 diabetes contraindicated diabetic ketoacidosis FDA safety
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SGLT2 inhibitors AND type 1 diabetes
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https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/20…
SGLT2 inhibitors are generally not used in type 1 diabetes because they substantially increase the risk of diabetic ketoacidosis (DKA), often with only mildly elevated or normal glucose, called euglycemic DKA.
Why this happens
- SGLT2 inhibitors cause urinary glucose loss. Blood glucose falls even if insulin is insufficient.
- A person with T1DM may then reduce insulin, or have an unrecognized relative insulin deficiency.
- Low effective insulin plus higher glucagon promotes fat breakdown and hepatic ketone production.
- Glycosuria masks the usual marked hyperglycemia of DKA, so diagnosis can be delayed.
Common triggers include missed/reduced insulin doses, fasting or a low-carbohydrate diet, vomiting/illness, dehydration, surgery, excess alcohol, and insulin-pump failure.
Thus, the glucose-lowering benefit does not outweigh the DKA risk for routine T1DM treatment. FDA labeling notes that, in T1DM trials, ketoacidosis occurred more often with SGLT2 inhibitors than placebo, and can occur with glucose below 250 mg/dL. FDA prescribing information
Strictly speaking, in many product labels this is phrased as “not indicated” or “not recommended” for T1DM rather than an absolute pharmacologic contraindication. The central reason remains the same: increased, potentially life-threatening euglycemic DKA risk. This mechanism is also described in Katzung’s Basic and Clinical Pharmacology, where off-label T1DM use is associated with euglycemic DKA.
Why Levothyroxine should be given in empty stomach
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levothyroxine administration empty stomach absorption food calcium iron prescribing information
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levothyroxine AND food absorption
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Levothyroxine is given on an empty stomach because food makes its intestinal absorption lower and less predictable.
- It is absorbed mainly in the small intestine.
- Meals can delay and reduce absorption, so the same tablet dose may deliver less hormone on some days.
- Calcium, iron, antacids, fiber-rich foods, coffee, and some acid-suppressing drugs can further interfere by binding the drug or altering gastric conditions.
- Inconsistent absorption can lead to a raised or fluctuating TSH, making the hypothyroidism appear undertreated despite taking the prescribed dose.
Take the tablet with water, ideally 30-60 minutes before breakfast. An alternative is bedtime dosing, provided it is consistently at least 2-3 hours after the last meal. Keep calcium, iron, and antacids at least 4 hours apart. The DailyMed prescribing information gives the same timing recommendation.
Symptom to Diagnosis: An Evidence-Based Guide, 4th ed., notes that food can reduce levothyroxine absorption by about 40%.
Why Levothyroxine should be given in empty stomach
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Levothyroxine is best taken on an empty stomach because food can reduce and make absorption unpredictable. If less drug is absorbed, thyroid hormone levels may be too low and TSH may rise.
Take it with water 30-60 minutes before breakfast. Keep calcium, iron, antacids, and multivitamins at least 4 hours apart, because they can bind levothyroxine in the gut and further reduce absorption.
A consistent bedtime alternative is acceptable if taken at least 2-3 hours after the last meal.
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