Chapter 44: Diabetes Mellitus – Drug Therapy & Insulin Use

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Welcome to the Depth Dive.

Today we're plunging into what's really one of the most critical chronic disease challenges you'll face in advanced practice,

diabetes mellitus.

Absolutely, it's everywhere.

We've got a stack of research here focusing on the pharmacotherapy from our sources and we're going to try and distill it down into, you know, really actionable knowledge for you.

It's essential stuff.

I mean, the scale is just, it's huge.

You're looking at over 30 million people in the U .S.

with diabetes.

30 million, wow.

And the vast majority, maybe 90, 95 percent, that's type 2.

Plus you've got, what, 84 million or so with pre -diabetes.

Which is why it's the seventh leading cause of death.

It's serious.

Exactly.

So getting the treatment right is paramount.

Right.

So let's get the basics down first.

Diabetes mellitus.

It's not just one thing, is it?

It's defined by high blood sugar hyperglycemia.

But the why is different.

That's the key.

It's a group of disorders, really.

Type 1 is, well, it's an absolute lack of insulin.

Yeah.

The body's own immune system destroys the beta cells in the pancreas.

And that usually shows up earlier in life.

Typically, yes.

Younger on set.

Type 2, though, that's more of a combination issue.

Okay.

You've got cells becoming resistant to insulin.

Plus, the pancreas struggles to secrete enough insulin to compensate for that resistance.

And the big risk factors there are things like obesity, family history.

Those are the main drivers, yes.

Yeah.

So our goal today for you listening is to give you a solid rundown of the drugs used.

Uh -huh.

We'll cover how they work, when to use them, the big risks, and some clinical pearls you really need to know for advanced practice.

Straight from the source material.

Perfect.

Let's kick off with the why.

Why are these complex drug regimens?

What's the ultimate goal here?

It really boils down to preventing or at least slowing down those awful long -term complications.

The ones nobody wants to see.

Exactly.

We have solid evidence for this.

The big landmark trials, DCCT for type 1 and UK PDS for type 2, they clearly showed tight glycemic control makes a huge difference.

Slowing down things like eye problems, nerve damage.

Ritinopathy, neuropathy, nephropathy, yes.

Good control significantly slows progression.

But the targets like the A1C goal, they aren't one size fits all, are they?

How do you figure that out for each patient?

Ah, that's where clinical judgment really comes in.

It's all about individualization.

The ADA, the American Diabetes Association, generally suggests an A1C under 7 .0 percent for most adults.

Okay, under 7 .0.

But you might aim lower, maybe under 6 .5 percent, for someone who's younger, newly diagnosed, generally healthy, you know.

Right, be a bit more aggressive.

But on the flip side, for an older person, someone who's had diabetes for ages or has other major health issues, especially heart disease.

Then you might ease up a bit.

Exactly.

Maybe aim for under 8 .0 percent because the risk of severe hypoglycemia, low blood sugar, could actually be more dangerous for them than the benefit of supertech control.

It's a balance.

What about the daily finger stick goals?

There are differences there, too, right?

Between ADA and 8C.

Yeah, good point.

The ADA generally aims for pre -meal glucose between 80 and 130mgdL and under 180 after meals.

8Cs, the American Association of Clinical Endocrinology, tends to be a bit stricter.

They like to see under 110 before meals and under under 40 after.

It's important to know both sets of guidelines.

And it's not just about sugar, is it?

There are other crucial targets.

Oh, absolutely.

You've got to manage the whole picture.

Blood pressure is huge, often aiming for less than 30, 30, 80.

Lipids, too.

Like LDL cholesterol.

Yep, often aiming for a 50 percent reduction, maybe starting a high -dose statin if they have existing heart disease, and screening for kidney issues like microluminaria.

So before we even talk pills, what's step one for type two?

Lifestyle, lifestyle, lifestyle.

Cannot emphasize it enough.

Medical nutrition therapy, basically, diet changes, and regular physical activity.

Didn't the DPP study show lifestyle is even better than metformin for prevention?

It did.

The diabetes prevention program, the DPP, found intensive lifestyle changes cut the risk of developing type two by 58 percent.

Metformin reduced it by 31 percent.

Lifestyle is powerful.

Okay, but if lifestyle changes aren't enough, then we bring in the drugs.

Let's start with the old faithful, metformin.

Right, the workhorse.

Metformin is a big one -eyed.

It's usually the first drug started for type two.

Its main job is to stop the liver from making too much glucose.

It dials down gluconeogenesis.

Exactly, and glycogenolysis, too.

Plus, it helps peripheral tissues use insulin a bit better, but importantly, it doesn't force the pancreas to pump out more insulin.

And that lack of direct stimulation is its big safety advantage, isn't it?

That's the key takeaway.

Metformin, used alone, doesn't cause hypoglycemia, and it doesn't cause weight gain, which is a huge plus.

So clinically, how do you usually start it?

You start low, maybe 500 milligrams once or twice a day, or 850 milligrams once a day, and increase it slowly, maybe weekly.

Max dose depends on the formulation IR or ER.

And always take it with food.

Always with meals.

That helps minimize the main side effects, which are GI issues, diarrhea, nausea.

Now the big warnings.

Lactic acidosis, rare but serious, who absolutely shouldn't take metformin.

Anyone with severe kidney problems and EGFR less than 30, that's a definite no -go.

Also conditions like chronic alcohol abuse, severe liver disease, unstable heart failure.

And you have to hold it for certain imaging tests.

Right.

If a patient is getting IV contrast dye for a CT scan or something similar, you hold them at formin before, and usually for 48 hours after, until you know their kidney function is okay.

Good point.

And maybe watch B12 levels long term.

Yes, it can cause B12 deficiency over time.

So worth monitoring.

Okay, moving on from metformin, the sensitizer.

Let's talk about the stimulators, the sulfonylureas, older class.

Yeah, one of the oldest oral classes.

These work directly on the pancreas.

They bind to receptors on the beta cells.

And make them release insulin.

Exactly.

They close potassium channels, which opens calcium channels, and boom, insulin gets released quickly.

I think glyburide, gluposide, glyburide, the second gen ones are most common now.

But they come with a major downside.

Hypoglycemia.

That's the number one risk, especially in older adults or people with kidney issues.

And they often cause some weight gain, maybe two, three kilos.

So given those risks, why are they still used?

Is it mostly cost?

Cost is a big factor, yes.

They're effective at lowering A1C, and they're inexpensive, but you're trading off safety.

You must start low and tight -treat very carefully.

And obviously, no -go if someone has a sulfa allergy.

Definitely contraindicated then.

All right, let's look at the other main class of insulin sensitizers, the thysolid and deonies, TZDs.

How do these work differently from metformin?

Totally different mechanism.

TZDs work inside the cell nucleus.

They activate a receptor called PPAR gamma.

A nuclear receptor, so it changes gene expression.

Or slightly.

It changes how genes related to insulin action are expressed, making muscle, fat, and liver cells more sensitive to insulin.

It improves insulin action without stimulating secretion, and the effect tends to last.

But they have their own set of significant risks, especially heart -related.

Yes, the big one is fluid retention, edema, because they cause plasma volume expansion.

So they're generally not recommended for patients with symptomatic heart failure, specifically NYHA class 3 or 5.

And contraindicated in active liver disease.

Correct.

Also an interesting point, they can sometimes restore ovulation in women who aren't ovulating due to improved insulin sensitivity.

So contraception needs to be discussed.

And there was some concern about pioglitazone and bladder cancer?

There's been a signal, yeah.

Studies vary, but it's something listed as a possible risk, particularly with long -term high -dose use.

Okay, let's shift gears completely now.

Talk about drugs that work in the gut.

The alpha -glucosidase inhibitors.

Ecarbose, miglitol.

What's their strategy?

Their job is simple.

Slow down how quickly you absorb complex carbohydrates from your meal, right there in the small intestine.

So they mainly target after -meal spikes.

Post -perennial glucose.

Exactly.

They blunt that peak.

The key for patients is they must take it with the very first bite of each main meal.

First bite.

Got it.

And I'm guessing the side effects are mostly gut -related?

You guessed it.

Because you're delaying carb absorption, more carbs reach the colon, leading to fermentation.

So lots of gas, flatulence, sometimes diarrhea, bloating.

Which probably limits their use a bit.

It does tend to make them less popular compared to other agents, and they're contraindicated in conditions like inflammatory bowel disease or cirrhosis.

Right.

So we've covered the older guard, let's say.

Now for the newer players, starting with the incretin system.

The DPP4 inhibitors.

How do they leverage our own biology?

This is pretty cool, actually.

Our gut releases hormones called incretins, like GLP -1 and GIP, after we eat.

These hormones are responsible for maybe up to half of our insulin response to a meal.

Okay, natural helpers.

But there's an enzyme called DPP4 that breaks them down really quickly.

DPP4 inhibitors like cytaglyptin, linaglyptin, simply block that enzyme.

So you get more of your own natural incretins hanging around longer.

Exactly.

More active incretins mean better glucose control, especially after meals.

They're taken once daily.

And is there one that's easier to use if someone has kidney problems?

Yes, linaglyptin.

That's the unique one in the class because it doesn't need dose adjustment for kidney disease.

The others, like cytaglyptin, saxaglyptin, allogalyptin, usually do.

What about major warnings for this class?

Generally, low risk of hypoglycemia when used alone,

but there are warnings about hypersensitivity, severe joint pain arthralges, and a potential risk of pancreatitis, which can be serious.

And didn't a couple of them have heart failure concerns?

Yes, saxaglyptin and alloglyptin specifically have been linked to a potential increased risk of hospitalization for heart failure.

So something to consider in susceptible patients.

Okay, so if DPP4 inhibitors protect our natural incretins, the next class, the GLP1 receptor agonists, basically act like super potent versions of those incretins.

This is where things really started to change, right?

Oh, absolutely.

These agents, mostly injectables like liraglutide, dulaglutide, sambaglutide, though there is one oral form, rhabelsis, they mimic and enhance the effects of GLP1.

So they stimulate insulin release.

But only when glucose is high, it's glucose dependent.

They also suppress glucagon, which is a hormone that raises blood sugar, and importantly, they slow down how fast the stomach empties.

And that slowing effect has other benefits.

Big time.

It increases feelings of fullness,

satiety, which often leads to significant weight loss.

That's a major advantage for many type 2 patients.

And this class isn't just about lowering A1C anymore.

Talk about the, so what, the complication reduction.

This is the game changer.

Several of these agents,

liraglutide, duloglutide, injectable sambaglutide, have proven cardiovascular benefits.

Their FDA approved to reduce the risk of heart attacks, strokes, and cardiovascular death in patients with established heart disease.

Wow.

And kidney benefits too.

Yes.

They've also shown they can protect the kidneys, particularly by reducing albuminuria, which is an early sign of kidney damage.

So if your patient has heart disease or kidney disease,

these are top contenders now.

Absolutely.

They've moved way up in the treatment algorithm for those specific patient groups because they address the complications directly, not just the blood sugar number.

But they do come with a very specific, serious warning.

Yes.

The thyroid C -cell tumor risk.

It's a black box warning.

It was seen in rodent studies.

So who can't take these?

They are absolutely contraindicated.

If the patient or a family member has a history of medullary thyroid carcinoma, MTC, or a rare condition called multiple endocrine neoplegia syndrome type 2, MEN2.

Okay.

Critical point.

And maybe avoid in severe stomach problem.

Right.

Given the slow gastric emptying so much, you'd be cautious or avoid them in someone with severe gastroparesis, for instance.

All right.

That leads us logically to insulin itself.

Mandatory for type 1, often needed for type 2 eventually, or in specific situations like pregnancy or surgery.

Correct.

Insulin is life -saving for type 1.

For type 2, it often becomes necessary when other agents aren't enough or during times of high stress or severe hyperglycemia.

Let's break down the types.

Basal versus bolus.

Okay.

Basal insulins are your long -acting ones in glargine to tamir deglodex.

They provide a steady background level of insulin, mimicking the body's continuous secretion.

Covers you between meals and overnight?

Exactly.

Then you have bolus or prandial insulins.

These are rapid or short -acting like lispro, aspart, glulicine, or regular insulin.

You take these specifically to cover the carbs in your meals.

So for someone with type 1, starting insulin involves some math, right?

How do you estimate the initial dose?

It's usually based on weight.

A common starting point is 0 .4 to 0 .5 units per kilogram of body weight per day.

That's your taminate actor.

Total daily dose or TDD?

Okay.

TDD.

Then what?

You split that TDD.

Roughly 40 % to 50 % becomes the basal dose, often given once or twice a day.

The other 50 % to 60 % is divided up as bolus doses before meals.

Makes sense.

But for type 2, when you're maybe just adding basal insulin to oral meds, the approach is different.

Yeah.

Usually start lower and simpler.

Maybe 0 .1 to 0 .2 units per kilo per day or often just a flat dose like 10 units at bedtime.

And then adjust based on fasting sugars.

Right.

Chitrate it up every few days based on their morning fasting blood glucose readings until they're hitting their target range.

Now, a crucial concept for anyone on insulin, especially mealtime insulin, is the correction factor or insulin sensitivity factor.

How does that work?

This tells you how much one unit of rapid acting insulin is likely to lower that specific patient's blood glucose.

It's vital for correcting high readings.

And there's a formula.

A common one is the 1800 rule for rapid acting insulin.

You divide 1800 by the patient's total daily dose, TDD, of insulin.

So if someone's TDD is, say, 50 units.

Then 1800 divided by 50 is 36.

So their insulin sensitivity factor is 36.

That means one unit of rapid acting insulin should drop their blood sugar by about 36 milligDL.

That's super helpful for patients managing highs.

Okay.

Side effects of insulin, obviously hypoglycemia is number one.

Changes in fat tissue at injection sites.

Right.

Rotating sites is key to prevent that.

But let's talk about two phenomena that can really confuse things.

The Dawn Phenomenon and the Salmage Effect.

Why is it so important to tell them apart?

Because the treatment is the opposite.

If you misdiagnose, you make things much worse.

The Dawn Phenomenon is just a natural rise in blood sugar in the early morning, around 3 or 4 a .m., due to hormones like growth hormone.

Okay.

Happens to lots of people.

The Salmage Effect, though, is rebound hypoglycemia that happens after an episode of low blood sugar overnight, usually caused by too much evening or nighttime insulin.

The body overcorrects.

So if you think it's Dawn Phenomenon and give more insulin at night?

But it's actually Salmage Effect.

You could cause dangerous, severe hypoglycemia.

How do you usually sugar it out?

The key is checking blood sugar in the middle of the night, maybe around 2 or 3 a .m.

If it's low, then it's likely Salmage.

If it's normal or high, it's more likely Dawn.

Got it.

Before we wrap up insulin, quick mention of Afretza, the inhaled one.

Yes.

The only inhaled rapid -acting insulin.

Works fast.

Main thing to know is the big contraindication.

Chronic Lung Disease.

Nazma COPD.

Exactly.

Or active smokers.

It requires lung function testing before starting.

Okay.

Let's pull all these drug classes together.

Thinking about the type 2 treatment pathway or algorithm.

Metformin first, usually.

If A1C isn't at goal after, say, 3 months, what drives the choice for the second drug?

It's really shifted.

Now, it's heavily based on the patient's other conditions, their comorbidities, if they have established cardiovascular disease, ASCVD, heart failure, HF, or chronic kidney disease, CKD.

Then a GLP -1 receptor agonist, or an SGLT2 inhibitor, is strongly preferred.

Because of those proven cardio -renal benefits we talked about, they address the complications.

And if the main goal is weight loss or maybe just avoiding hypoglycemia?

Again, GLP -1 RAs or SGLT2 inhibitors are generally the top choices there, too.

They help with weight and have low hypo risk.

But what if cost is the biggest barrier for the patient?

Ah, that's where the older agents still have a role.

If cost is the primary issue, then adding a sulfonylurea or a TZD to metformin is a reasonable, effective strategy, despite the risks we discussed.

Makes sense.

So,

regardless of which drugs we choose, patient education seems absolutely vital.

What are the non -negotiable teaching points?

Oh, critical.

First, hypoglycemia.

Every patient needs to know the symptoms shaky, sweaty, confused, and exactly what to do.

Always carry a fast -acting sugar source.

Like 15 grams of carbs, glucose tabs, juice?

Exactly.

Four ounces of juice, hard candies.

Yeah.

And second, sick day rules.

This is huge.

What happens when they get the flu or something?

They absolutely must not stop their diabetes meds, especially insulin, even if they're not eating much.

Illness itself raises blood sugar.

Stress response.

Right.

So, keep taking meds, drink plenty of fluids, water, sugar -free drinks, maybe eight ounces an hour, and check blood sugar much more often.

Maybe check for ketones and urine, too.

And when should they call the clinic or seek help?

If blood glucose stays really high, say over 300mgdl on two checks in a row, or if they have moderate to large ketones, vomiting, signs of dehydration, they need formal evaluation right away.

Excellent summary.

So, we've really covered a lot of ground today, from metformin and sulfonylureas, the older guard, through the TZDs, the gut agents, and then the really transformative incretin therapies and modern insulins.

Yeah, it's a complex landscape.

And the big theme seems to be the shift towards picking drugs not just for A1C, but to actually reduce the risk of those devastating long -term complications, especially with the GLP -1s and SGLT -2s.

It's definitely the direction things have moved, focusing on that individualized, complication -centered care.

So, thinking ahead, what's one final thought or trend you see really shaping how we manage diabetes going forward?

Well, building on that idea of personalization.

It's got to be continuous glucose monitoring, CGM.

We're moving beyond just that three -month snapshot of the A1C.

Right.

CGM gives you the movie, not just the photo.

Exactly.

It shows the patient and the provider the immediate impact of food, activity, stress, medication, moment by moment.

It allows for such fine -tuned adjustments and really empowers patients.

It's shifting care from quarterly check -ins to almost real -time, highly personalized management.

A fascinating glimpse into the future of diabetes care.

Well, that brings us to the end of this deep dive.

Thanks so much for walking us through this complex topic.

My pleasure.

It's crucial information.

And a big thank you to you, our listeners, for joining us.

We hope this breakdown of diabetes pharmacotherapy helps you connect the dots in your practice.

From the Last Minute Lecture Team, thanks for tuning in.