DPP-4 Inhibitors

Dipeptidyl peptidase-4 inhibitors (DPP-4 inhibitors), also called gliptins, are a class of oral glucose-lowering medications used to treat type 2 diabetes mellitus. Their biological rationale derives from pharmacological enhancement of the incretin axis, the physiological system through which the intestine informs the pancreas that a nutrient load has arrived and modulates insulin and glucagon secretion in a glucose-dependent manner. In practical terms, gliptins do not replace insulin, do not act as nonselective secretagogues and do not induce urinary caloric loss like sodium-glucose cotransporter 2 (SGLT2) inhibitors; instead, they improve glycemic control mainly by attenuating postprandial hyperglycemia and, to a lesser extent, fasting hyperglycemia, with a generally favorable tolerability profile.

The class mainly includes sitagliptin, linagliptin, saxagliptin, alogliptin and, in some regulatory settings, vildagliptin. Their historical clinical importance has been considerable because they represented the first simple oral means of harnessing the incretin effect without directly administering glucagon-like peptide 1 receptor agonists (GLP-1 RAs). Their current therapeutic positioning has nevertheless changed: they remain useful medications in selected patients, particularly when ease of use, weight neutrality, a low risk of hypoglycemia and good gastrointestinal tolerability are required, but they no longer occupy the top tier of treatment hierarchies in people with obesity, atherosclerotic cardiovascular disease, heart failure or chronic kidney disease, settings in which other classes have demonstrated more robust benefits beyond glycemic control.

DPP-4 inhibitors became established in the treatment of type 2 diabetes mellitus at a time when there was a particularly strong need for effective, manageable oral medications with a lower risk of hypoglycemia than sulfonylureas and meglitinides. Their uptake was supported by four features: oral administration, usually once-daily dosing, no clinically relevant weight gain and generally good tolerability, especially compared with medications that cause nausea, diarrhea or edema. For many years, this combination of advantages made them a frequent second-line choice after metformin or an option for older or frail patients and those with moderate glycemic targets.

As cardiovascular and renal outcome data progressively accumulated, however, the role of the class was reassessed. Large randomized trials primarily demonstrated cardiovascular safety in terms of noninferiority, but not a consistent reduction in major events comparable to that observed with some GLP-1 receptor agonists or SGLT2 inhibitors. In other words, gliptins showed that, as a class, they do not meaningfully worsen overall cardiovascular risk, but neither do they produce, apart from weak or neutral signals, the prognostic benefit that now decisively guides medication selection in high-risk patients.

This change in the therapeutic landscape has had a direct impact on guidelines. In contemporary diabetology, pharmacological decisions are no longer based solely on lowering glycated hemoglobin, but on an integrated model that considers obesity, risk of hypoglycemia, cardiovascular comorbidities, kidney function, patient preferences, cost, route of administration and long-term sustainability. Within this framework, gliptins have become a class with selective utility, less central than in the past but not obsolete.

They remain particularly useful when the clinician wants an easily managed oral medication that does not cause weight gain, has a low risk of hypoglycemia and imposes few restrictions on daily life. This applies to people with type 2 diabetes mellitus who are not far from target, in whom the main goal is to fine-tune glycemic control without adding therapeutic complexity, or to patients who do not tolerate the gastrointestinal effects of more potent injectable or oral incretin-based therapies.

Moreover, the class is not homogeneous in every practical respect. Linagliptin is distinguished by the absence of a need for dose adjustment in kidney failure, whereas sitagliptin requires adjustment according to estimated glomerular filtration rate; saxagliptin warrants greater caution in patients at risk of heart failure; and vildagliptin has a history of specific attention to liver function. These within-class differences explain why selection should never be abstract, but instead linked to the individual active substance and the individual patient.

Their current use must therefore be understood from both a historical and hierarchical perspective. They are no longer the preferred solution when weight loss, cardiorenal protection or reduction of major-event risk is sought. They nevertheless remain medications with a rational place in patients for whom simplicity, glycemic safety and clinical acceptability predominate. Correctly interpreting their role in treatment means neither overestimating nor underestimating them: they are not leading medications in high-risk cardiometabolic phenotypes, but neither are they marginal when the patient’s clinical profile aligns with their strengths.

A full understanding of DPP-4 inhibitors begins with the physiology of incretins. After nutrients, particularly carbohydrates and fats, are ingested, the intestine releases hormones such as glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide (GIP). These peptides amplify glucose-stimulated insulin secretion, partly suppress glucagon secretion when blood glucose is elevated and help coordinate the postprandial metabolic response. In type 2 diabetes mellitus, the incretin effect is attenuated, owing both to alterations in secretion and, above all, to reduced functional effectiveness of the system.

DPP-4 is a widely expressed serine protease, present both as a membrane-bound enzyme and as a soluble circulating form. Its action consists of rapidly cleaving several peptides that contain a specific N-terminal amino acid sequence. Among the most metabolically relevant substrates are GLP-1 and GIP themselves, which are inactivated very rapidly after release. Pharmacological inhibition of DPP-4 therefore prolongs the fraction of biologically active incretins and extends physiological incretin signaling.

The principal effects of the class derive from this mechanism. The first is a glucose-dependent increase in insulin secretion by pancreatic beta cells. This point is crucial because it explains the low risk of hypoglycemia during monotherapy: the medication does not force insulin secretion independently of the blood glucose level, but enhances a circuit that operates mainly when glucose is elevated. The second effect is reduction of inappropriate glucagon secretion in the postprandial state, attenuating hepatic glucose production. The third is better control of glucose after meals, often the metabolic target most responsive to the class.

Unlike GLP-1 receptor agonists, gliptins generally do not cause clinically important slowing of gastric emptying and do not induce a marked reduction in food intake. Their impact on body weight is therefore essentially neutral. This weight neutrality can be advantageous relative to medications associated with weight gain, but it is also why the class does not compete, in patients with obesity, with treatments that provide a clear weight benefit.

The overall metabolic benefit of the class is moderate. In most studies, the decrease in glycated hemoglobin is roughly around half a percentage point, with the magnitude varying according to baseline glycated hemoglobin, beta-cell reserve, background therapy and the agent used. Efficacy is more apparent when the medication is introduced before the disease becomes too advanced, while a functional degree of endogenous insulin secretion remains. In long-standing diabetes, severe beta-cell deficiency or marked hyperglycemia, the corrective capacity of the class tends instead to be insufficient.

Pharmacokinetically, gliptins share a biological target but differ in absorption, metabolism and elimination. Sitagliptin is eliminated predominantly by the kidneys and requires dose reduction as glomerular filtration rate declines. Linagliptin is eliminated predominantly by nonrenal routes, making it particularly practical in patients with chronic kidney disease. Saxagliptin is also metabolized through cytochrome P450 3A4/5 (CYP3A4/5), which makes interactions with strong enzyme inducers or inhibitors more relevant. Vildagliptin and alogliptin have intermediate profiles, but specific regulatory precautions must be remembered.

There is also a less intuitive but important point: DPP-4 inhibition does not affect incretins alone. The enzyme also participates in regulating other peptides involved in inflammation, immunity, vascular tone and tissue signaling. In theory, this has prompted hypotheses of pleiotropic anti-inflammatory or vascular effects, but in clinical practice hard outcomes have not confirmed a systematic benefit sufficient to change the prognostic profile of the class. This is a key distinction between biological potential and clinically demonstrated benefit.

This leads to a precise pharmacological conclusion: gliptins elegantly exploit a genuine physiological circuit, but do so with limited clinical potency. Their value lies not in radically transforming the metabolic phenotype, but in measured optimization of glycemic control in selected settings, with little impact on weight or hypoglycemia. Their therapeutic identity therefore arises from the combination of a refined mechanism, moderate efficacy and ease of use.

The clinical place of DPP-4 inhibitors depends on the type of problem the physician needs to solve. When the goal is a moderate reduction in glycated hemoglobin without increasing body weight, introducing injections or significantly raising the risk of hypoglycemia, the class retains a rationale. This profile makes it particularly useful in patients with type 2 diabetes mellitus who are relatively close to target, do not have extreme hyperglycemia and need a simple addition to their current therapy.

The typical patient who may benefit from a gliptin is often an adult or older person with suboptimal control on metformin monotherapy, without a priority need for weight loss or a clear cardiorenal indication for other classes. In these cases, a gliptin can improve the glycemic profile with good tolerability, minimal interference with daily life and a low risk of hypoglycemic episodes, qualities that are particularly valuable in a frail person, someone living alone or an individual with variable meal intake.

Another relevant setting is the patient with chronic kidney disease. Here, selection of the individual medication is crucial. Linagliptin is often considered practical precisely because it does not require dose adjustment according to kidney function, whereas sitagliptin and other agents do require adjustment. Prescribing convenience, however, must not be confused with a specific nephroprotective benefit: gliptins can be used in kidney disease, but they are not the reference class when the primary target is to slow progression of renal disease.

The class may also be considered for patients who cannot tolerate the gastrointestinal burden of other incretin-based therapies or who decline injections. Gliptins offer the advantage of a simple oral approach, with a lower likelihood of nausea and vomiting. However, if the patient has obesity, high cardiovascular risk or needs a larger reduction in blood glucose, their use should be weighed carefully because they may be less effective than alternative options.

In patients already receiving a sulfonylurea or insulin, a DPP-4 inhibitor can be added, but the risk of hypoglycemia caused by background therapy must be assessed. Gliptins rarely cause hypoglycemia by themselves; the problem arises when they are incorporated into regimens containing medications that can lower blood glucose independently of the metabolic context. In such cases, reducing the secretagogue dose or adjusting insulin may be reasonable.

There are also settings in which the class is less suitable. It is not a preferred choice in type 2 diabetes mellitus with clinically relevant obesity because it does not promote weight loss. It is not the first option when proven cardiovascular or renal protection is sought. It is unsuitable for type 1 diabetes mellitus and diabetic ketoacidosis. It should not be routinely combined with GLP-1 receptor agonists because combining two therapies that act on the incretin system generally provides no proportionate benefit and unnecessarily increases complexity and cost.

The metabolic phenotype also guides selection. In people with marked fasting hyperglycemia, substantial glucotoxicity, evident beta-cell decline or catabolic symptoms, the corrective capacity of gliptins is usually insufficient. These situations require more potent or more rapidly acting therapy. Conversely, their rationale is stronger in patients with predominantly postprandial hyperglycemia and a moderate increase in glycated hemoglobin.

Correct clinical use of the class therefore depends on recognizing that DPP-4 inhibitors are not universal medications, but relatively precise tools for specific problems. Their strength is not maximum absolute efficacy, but a favorable balance among sufficient efficacy, tolerability, simplicity and glycemic safety in carefully selected patients.

The efficacy of DPP-4 inhibitors should be evaluated across at least four domains: reduction in glycated hemoglobin, effect on postprandial glucose, impact on body weight and risk of hypoglycemia. In the first domain, the class shows consistent but moderate efficacy. The benefit is more apparent in patients with higher baseline glycated hemoglobin and residual beta-cell function, whereas it diminishes in advanced stages of type 2 diabetes mellitus. This profile makes the class poorly suited as the sole solution when glycemic control is markedly off target.

The effect on postprandial glucose is often the most consistent feature of the class. Because the mechanism depends on amplification of the incretin axis, the metabolic response after a meal is the setting in which the pharmacological effect is expressed most consistently. Clinicians may therefore observe appreciable improvements in postmeal glucose excursions even when the absolute decrease in glycated hemoglobin is not dramatic.

The finding for body weight is clear: gliptins are largely weight-neutral. This favorably distinguishes them from sulfonylureas, insulin and thiazolidinediones, but makes them less attractive than GLP-1 receptor agonists and newer incretin-based medications when excess weight is an important therapeutic target. Weight neutrality is an advantage in terms of safety and acceptability, but does not translate into an improvement in visceral adiposity comparable to that provided by weight-loss classes.

With regard to hypoglycemia, the class ranks among the safest when it is not combined with secretagogues or insulin. This has enormous clinical value in older adults, patients at risk of falls, people with impaired awareness of hypoglycemia and settings in which marked glucose fluctuations must be avoided. Its hypoglycemic safety is probably one of the main reasons the class continues to have a role despite the emergence of more potent therapies.

Comparison with other classes further clarifies their position. Relative to metformin, gliptins are less effective as the initial metabolic foundation and do not share the same tradition as a general first-line therapy. Relative to sulfonylureas, they cause less hypoglycemia and no weight gain, but often do not lower glucose more effectively. Relative to thiazolidinediones, they are simpler and better tolerated, but do not have the same effect on insulin resistance. Relative to SGLT2 inhibitors and GLP-1 receptor agonists, they lose ground when the clinician is targeting cardiorenal protection or weight loss.

Large cardiovascular trials have precisely defined the message for this class. TECOS with sitagliptin, EXAMINE with alogliptin and CARMELINA with linagliptin essentially confirmed noninferiority to placebo in terms of cardiovascular safety. SAVOR-TIMI 53 with saxagliptin, although it also confirmed neutrality for the primary ischemic composite, raised a specific concern regarding hospitalization for heart failure. This finding influenced clinical perceptions of the agent and, more broadly, reinforced the view that the class should not automatically be considered neutral in every respect for every patient.

The renal picture is similar. Gliptins can be used in many patients with reduced kidney function, and some, such as linagliptin, are particularly convenient in this regard. The evidence, however, does not show a structural nephroprotective benefit comparable to that observed with SGLT2 inhibitors. Their presence in the regimen of a patient with kidney disease should therefore be viewed as therapeutic compatibility, not as a first-line choice to modify the natural history of diabetic kidney disease.

A critical reading of the evidence therefore requires a fundamental distinction between glycemic control and hard outcomes. Gliptins manage the former well, to a moderate degree and safely. They have not demonstrated the same strength in improving the latter. For this reason, some contemporary recommendations have downgraded them as a standard add-on option when the stated goal is to reduce mortality, cardiovascular events or kidney disease progression. In practice, scientific judgment of the class is favorable in terms of metabolic manageability but more reserved in terms of prognosis.

Discussing DPP-4 inhibitors as though they were completely interchangeable is useful for understanding the class, but insufficient for good prescribing. Available agents share the pharmacological target, yet differ in elimination, dosing, interactions and, to some extent, regulatory safety profile. Understanding these differences is essential because, in clinical practice, it is often the within-class detail that determines the choice.

Sitagliptin is one of the most extensively studied and widely used agents. It offers the advantages of long clinical experience, simple administration and reassuring cardiovascular data in terms of neutrality. Its most important practical consideration is the need to reduce the dose in kidney failure, using different regimens according to glomerular filtration rate. This requires prescribing attention but does not preclude its use in patients with kidney disease.

Linagliptin has acquired a particular position because it requires no dose adjustment according to kidney function. This makes it very attractive in patients with chronic kidney disease, especially when therapeutic simplification is sought. It has also shown essentially neutral cardiovascular safety. Its clinical identity is therefore closely linked to its practicality in patients with kidney disease.

Saxagliptin retains the glycemic efficacy of the class, but its profile is marked by the signal from SAVOR-TIMI 53 of increased hospitalization for heart failure. Although the precise biological significance remains debated and not all exposed patients have the same risk, this observation changed how the agent is viewed. In the presence of a history of heart failure or a high-risk clinical setting, many clinicians prefer to avoid saxagliptin or use it with particular caution.

Alogliptin showed essentially neutral cardiovascular safety in EXAMINE, which enrolled patients with a recent acute coronary syndrome. This agent has also attracted regulatory attention regarding heart failure, although the signal did not acquire the same symbolic weight as that associated with saxagliptin. In practice, its use depends considerably on local availability and the prescriber’s experience.

Vildagliptin, although it shares the incretin-based mechanism, has a distinctive history regarding monitoring of liver function. Regulatory information has emphasized the need to check transaminases before treatment and periodically during the first year, discontinuing therapy if a significant persistent increase occurs. This does not mean that the medication is ordinarily severely hepatotoxic in clinical terms, but it imposes a practical precaution that distinguishes it from other gliptins.

In addition to differences in elimination and safety, there are differences in drug interactions. Because CYP3A4/5 is involved in its metabolism, saxagliptin is more susceptible to changes in concentration in the presence of strong enzyme inhibitors or inducers. Linagliptin and sitagliptin generally have a simpler interaction profile, which can be advantageous in patients receiving multiple medications.

From a practical standpoint, the most relevant distinguishing features can be summarized as follows.

• Sitagliptin: extensive clinical experience, cardiovascular neutrality, renal dose adjustment.
• Linagliptin: class-level efficacy, good manageability, no renal dose adjustment.
• Saxagliptin: class-level efficacy, but caution in heart failure and attention to CYP3A4/5 interactions.
• Alogliptin: cardiovascular neutrality, with use depending on availability and the prescribing setting.
• Vildagliptin: class-level efficacy with a need for more structured liver monitoring.

These differences clearly illustrate a general principle of modern diabetology: there is almost never a choice that is valid in the abstract. Even within a class that shares a mechanism, the right medication emerges from the intersection of kidney function, cardiovascular risk, comorbidities, polypharmacy, ease of management and the dominant clinical objective.

DPP-4 inhibitors should be used within a reasoned treatment pathway, not as an isolated prescribing act. In most cases, the class enters as combination therapy rather than as the initial foundation of treatment. The most typical setting is addition to metformin when glycemic control remains suboptimal and neither cardiorenal risk reduction nor weight loss is the patient’s main clinical priority.

The combination with metformin is historically one of the most rational. Metformin acts mainly by reducing hepatic glucose production and improving the overall metabolic profile, whereas the gliptin acts through the incretin and postprandial pathways. The complementary mechanisms provide a glycemic benefit without an excessive burden of adverse effects. Fixed-dose metformin-plus-gliptin combinations have therefore been widely used.

Combination with sulfonylureas is possible but less elegant. Both classes increase effective insulin availability, but through different mechanisms. The gliptin does so in a glucose-dependent manner; the sulfonylurea does not. Consequently, the gliptin’s advantage in terms of hypoglycemic safety may be partly lost when it is added to a secretagogue. In such cases, it is often appropriate to reconsider the sulfonylurea dose or assess whether the combination is truly the best choice.

Combination with basal insulin can be useful in patients whose glycemic control, particularly postprandial control, needs to be fine-tuned without immediately introducing more complex insulin regimens. A gliptin may reduce the need for overly rapid insulin intensification and limit weight gain, but its efficacy remains moderate. As insulin requirements rise or hyperglycemia becomes substantial, the contribution of the class tends to become marginal.

Combination with SGLT2 inhibitors is pharmacologically possible and is sometimes used, especially in patients who cannot receive other therapies or who require multiple oral add-on medications. In the current setting, however, when only one add-on class with additional prognostic value is to be selected, SGLT2 inhibitors or GLP-1 receptor agonists often take priority. A gliptin may be added to refine glycemic control, not as the cornerstone of systemic benefit.

An important practical rule is not to routinely combine a DPP-4 inhibitor with a GLP-1 receptor agonist. Both therapies act on the incretin axis, but a GLP-1 receptor agonist already provides potent pharmacological receptor stimulation, making the additional benefit of DPP-4 inhibition generally modest and poorly justified in terms of cost-effectiveness.

Contemporary guidelines accurately reflect this setting. When a patient has atherosclerotic cardiovascular disease, heart failure, chronic kidney disease or obesity, other classes are typically preferred. DPP-4 inhibitors have a place in patients without these dominant priorities, or when tolerability limitations, contraindications, refusal of injections or the need for a simple, well-accepted oral therapy are present.

In practice, the appropriate positioning of the class can be summarized as follows.

• A reasonable add-on to metformin when a moderate glucose reduction with a low risk of hypoglycemia is needed.
• A particularly useful choice when a simple, weight-neutral and well-tolerated oral therapy is desired.
• A less competitive choice when the primary objective is weight loss, cardiorenal protection or a large reduction in blood glucose.
• A choice to individualize by agent, especially according to kidney function, heart-failure risk and liver profile.
• A choice to avoid in routine combination with GLP-1 receptor agonists.

Appropriate use therefore depends not on a fixed hierarchy, but on consistency between the clinical problem and the properties of the class. Prescribing a gliptin makes sense when the expected advantage truly matches what the medication can offer. When the patient instead requires a benefit that the class has not demonstrated, the choice is weak both pathophysiologically and prognostically.

The safety profile of DPP-4 inhibitors is generally favorable, but their apparent simplicity should not lead to trivialization of their use. As with all pharmacological classes, the crucial issue is not only which adverse events may occur, but in which patient they become clinically relevant. Most people tolerate gliptins well, with a relatively low rate of discontinuation due to adverse events; nevertheless, several areas of concern must be understood precisely.

The most important favorable safety feature is the low risk of hypoglycemia during monotherapy or combination with medications that do not themselves cause hypoglycemia. This advantage diminishes when a gliptin is used with sulfonylureas or insulin, in which case the clinician should consider reducing the doses of concomitant medications. Hypoglycemic safety is therefore not an absolute property of the class, but a contextual property related to the treatment combination.

From a cardiovascular standpoint, the most debated issue is heart failure. The signal observed with saxagliptin in SAVOR-TIMI 53 prompted a cautious approach, especially in patients with a history of heart failure or predisposing factors such as advanced kidney disease. Alogliptin has also received regulatory attention in this regard. This does not mean that every gliptin is automatically contraindicated in heart failure, but it requires careful assessment of the patient’s profile and the selected agent.

Another important issue is the possible association with acute pancreatitis. The subject has long been debated, and the overall evidence has not clearly confirmed a consistent increase in risk as a universally demonstrated class effect. Nevertheless, as a matter of clinical prudence, the onset of severe persistent abdominal pain, significant nausea or a suspicious rise in pancreatic enzymes during treatment requires prompt evaluation and, if necessary, discontinuation. In patients with previous pancreatitis, the risk-benefit balance should be considered carefully.

Cases of severe joint pain associated with gliptins have also been described. This is an uncommon event but is well documented in postmarketing reports. A characteristic feature is possible symptom resolution after discontinuation and recurrence upon re-exposure. Therefore, newly developing severe arthralgia during treatment should not be dismissed as nonspecific without considering the medication.

An increasingly recognized issue is the association between gliptins and bullous pemphigoid, particularly in older adults and with some agents more frequently implicated in pharmacovigilance reports. The absolute risk remains low, but the finding is clinically relevant because the condition may be overlooked in its early stages. Bullous lesions, persistent pruritus or atypical dermatoses in patients receiving long-term DPP-4 inhibitor therapy should prompt consideration of this possibility.

With regard to the liver, as already noted, vildagliptin warrants specific attention to transaminase monitoring. Regulatory product information recommends testing before treatment and periodically during the first year, with discontinuation in the event of a persistent, clinically significant increase. This feature is not shared identically by every agent in the class and confirms that pharmacovigilance must remain molecule-specific.

There are also the traditional class contraindications or settings in which the class is not indicated: type 1 diabetes mellitus, diabetic ketoacidosis, known hypersensitivity to the medication, and caution in clinical circumstances in which modest efficacy would make treatment inadequate. Some agents require caution with strong enzyme inducers, while others require adjustment in kidney failure.

In summary, gliptins are generally manageable medications, but their safety does not mean that surveillance is unnecessary. Appropriate monitoring consists of checking kidney function for dosing where necessary, considering heart-failure risk when selecting the agent, recognizing signs of pancreatitis, important arthralgia or bullous pemphigoid early, and applying the specific hepatic precautions required for vildagliptin.

Follow-up of patients receiving DPP-4 inhibitors does not generally require the complexity associated with other classes, but it must be methodical. The first step is to determine whether the medication is actually achieving the expected clinical result. Because gliptins have moderate efficacy, there is a genuine risk of continuing an ineffective treatment for too long. Reassessment of glycated hemoglobin after an appropriate interval, together with analysis of fasting and postprandial glucose, makes it possible to establish whether the benefit is real or merely theoretical.

A second point concerns kidney function. In patients treated with sitagliptin and other predominantly renally eliminated agents, estimated glomerular filtration rate should be checked periodically because correct dosing depends on it. The most common error is not prescribing the medication in a patient with kidney disease, but failing to adjust it when kidney function worsens. This practical problem is reduced with linagliptin, but kidney-function monitoring remains necessary for the overall management of diabetes.

It is also important to ask patients actively about tolerability. Although most people tolerate gliptins well, follow-up should include questions about abdominal pain, persistent nausea, skin eruptions, pruritus, substantial arthralgia, or symptoms suggestive of fluid retention and heart failure in vulnerable patients. A medication that is well tolerated in general may prove unsuitable for an individual if specific adverse signals emerge.

Therapeutic inertia must be avoided over the long term. If the reduction in glycated hemoglobin is insufficient after an adequate period, or if the patient develops new clinical priorities such as progressive obesity, kidney disease, heart failure or atherosclerotic cardiovascular disease, the role of the gliptin should be reconsidered. Ease of administration does not justify continuing a medication when the patient’s profile calls for a strategy with greater prognostic value.

Follow-up should therefore be dynamic. In some patients, a gliptin remains appropriate for years because it continues to provide an acceptable balance between control and tolerability. In others, it represents only a transitional stage before more potent therapies or treatments better targeted to comorbidities are introduced. Intelligent management of the class consists precisely in using it well and, when necessary, moving beyond it at the right time.

Monitoring has a different emphasis in older or frail patients. Here, the value of the medication may lie more in stability than in the maximum intensity of glycemic control. In such cases, targets should be consistent with the risk of hypoglycemia, cognitive function, adherence and the overall treatment burden. A gliptin may retain a meaningful advantage precisely because it allows useful simplification without pushing the patient toward regimens burdened by adverse events or poor acceptability.

Well-conducted follow-up therefore does not merely measure glycated hemoglobin. It assesses actual efficacy, dose appropriateness, emergence of new risk factors, tolerability, consistency of the medication with current objectives, and opportunities for deintensification or replacement. This approach avoids both underuse and inappropriate persistence of the class.

The final assessment of DPP-4 inhibitors should be balanced. They are valid medications based on a sound physiological mechanism and capable of improving glycemic control safely and simply. They made an important contribution to the transition from diabetology focused only on blood glucose to treatment that pays greater attention to tolerability and hypoglycemic risk. From this perspective, their historical and practical value is unquestionable.

At the same time, their limitations are now well defined. Their glycemic efficacy is moderate. Body weight is not significantly reduced. Cardiovascular and renal outcomes are largely neutral and have not placed the class among the pillars of modern cardiometabolic treatment. Moreover, specific concerns, such as caution with saxagliptin in heart failure and attention to rare but relevant adverse events, remind us that the class is not without drawbacks.

Their future therefore appears to depend less on expansion and more on appropriate selection. Gliptins will probably continue to be used in patients for whom manageability, oral administration, a low risk of hypoglycemia and weight neutrality are most important, or when other classes are contraindicated, poorly tolerated or inaccessible. In this sense, their therapeutic space becomes narrower but more clearly defined.

Research prospects focus mainly on three areas. The first is better identification of the clinical phenotypes most likely to benefit from the class, particularly among older adults, patients with kidney disease and people who need simple regimens. The second is clarification of the mechanisms underlying rare adverse events, such as bullous pemphigoid and severe arthralgia. The third concerns the possible role of increasingly advanced incretin-based molecules, which are effectively redefining the place of gliptins by comparison rather than through direct competition.

Overall, DPP-4 inhibitors are not the most advanced frontier in the treatment of type 2 diabetes mellitus, but they remain a useful, predictable and clinically sound class when selected for the right reasons. Their value today lies not in promising what they cannot deliver, but in reliably providing what they actually do well: a modest improvement in glycemic control that is simple to manage and generally well tolerated in carefully selected patients.