Diagnosticar Conjugation in Spanish
The Spanish verb diagnosticar means to diagnose, and it is a verb you will use again and again once you know it. Diagnosticar is a spelling-changing -ar (c → qu before e) verb, so the tables below show you exactly how it behaves in every tense. It has a spelling change (c → qu before e), which keeps the pronunciation of the stem the same when the ending changes. On this page you will find the full conjugation of diagnosticar in all thirteen tenses, notes on when to use each one, example sentences, the mistakes learners make most often, a ten-question quiz and answers to the questions students ask about this verb. For example, in the present tense you say Yo diagnostico la enfermedad — "I diagnose the illness" — and in the preterite you say Yo diagnostiqué a tiempo — "I diagnosed in time". Work through the tables below, read the notes for each tense, and then test yourself with the examples, the common mistakes and the quiz at the end of the page.
Quick facts
- Infinitive: diagnosticar
- English: to diagnose
- Verb type: spelling-changing -ar (c → qu before e) verb
- Ending: -ar
- Gerund: diagnosticando
- Past participle: diagnosticado
- Auxiliary verb: haber (all perfect tenses are formed with haber + diagnosticado)
Pronunciation is not listed on this page: the verified tables do not include IPA for diagnosticar, so no pronunciation is given rather than an invented one.
Full conjugation tables
Every form below comes from the verified conjugation tables for diagnosticar. The imperfect subjunctive is shown in its -ra forms; the -se forms use the same stem. For reflexive verbs, the pronoun column shows the reflexive pronoun that goes before each form.
Gerund: diagnosticando · Past participle: diagnosticado
Present indicative
| Person | Form |
|---|---|
| yo | diagnostico |
| tú | diagnosticas |
| él/ella/Ud. | diagnostica |
| nosotros/as | diagnosticamos |
| vosotros/as | diagnosticáis |
| ellos/ellas/Uds. | diagnostican |
Preterite
| Person | Form |
|---|---|
| yo | diagnostiqué |
| tú | diagnosticaste |
| él/ella/Ud. | diagnosticó |
| nosotros/as | diagnosticamos |
| vosotros/as | diagnosticasteis |
| ellos/ellas/Uds. | diagnosticaron |
Imperfect
| Person | Form |
|---|---|
| yo | diagnosticaba |
| tú | diagnosticabas |
| él/ella/Ud. | diagnosticaba |
| nosotros/as | diagnosticábamos |
| vosotros/as | diagnosticabais |
| ellos/ellas/Uds. | diagnosticaban |
Future
| Person | Form |
|---|---|
| yo | diagnosticaré |
| tú | diagnosticarás |
| él/ella/Ud. | diagnosticará |
| nosotros/as | diagnosticaremos |
| vosotros/as | diagnosticaréis |
| ellos/ellas/Uds. | diagnosticarán |
Conditional
| Person | Form |
|---|---|
| yo | diagnosticaría |
| tú | diagnosticarías |
| él/ella/Ud. | diagnosticaría |
| nosotros/as | diagnosticaríamos |
| vosotros/as | diagnosticaríais |
| ellos/ellas/Uds. | diagnosticarían |
Present perfect
| Person | Form |
|---|---|
| yo | he diagnosticado |
| tú | has diagnosticado |
| él/ella/Ud. | ha diagnosticado |
| nosotros/as | hemos diagnosticado |
| vosotros/as | habéis diagnosticado |
| ellos/ellas/Uds. | han diagnosticado |
Pluperfect
| Person | Form |
|---|---|
| yo | había diagnosticado |
| tú | habías diagnosticado |
| él/ella/Ud. | había diagnosticado |
| nosotros/as | habíamos diagnosticado |
| vosotros/as | habíais diagnosticado |
| ellos/ellas/Uds. | habían diagnosticado |
Future perfect
| Person | Form |
|---|---|
| yo | habré diagnosticado |
| tú | habrás diagnosticado |
| él/ella/Ud. | habrá diagnosticado |
| nosotros/as | habremos diagnosticado |
| vosotros/as | habréis diagnosticado |
| ellos/ellas/Uds. | habrán diagnosticado |
Conditional perfect
| Person | Form |
|---|---|
| yo | habría diagnosticado |
| tú | habrías diagnosticado |
| él/ella/Ud. | habría diagnosticado |
| nosotros/as | habríamos diagnosticado |
| vosotros/as | habríais diagnosticado |
| ellos/ellas/Uds. | habrían diagnosticado |
Present subjunctive
| Person | Form |
|---|---|
| yo | diagnostique |
| tú | diagnostiques |
| él/ella/Ud. | diagnostique |
| nosotros/as | diagnostiquemos |
| vosotros/as | diagnostiquéis |
| ellos/ellas/Uds. | diagnostiquen |
Imperfect subjunctive (-ra)
| Person | Form |
|---|---|
| yo | diagnosticara |
| tú | diagnosticaras |
| él/ella/Ud. | diagnosticara |
| nosotros/as | diagnosticáramos |
| vosotros/as | diagnosticarais |
| ellos/ellas/Uds. | diagnosticaran |
Imperative (affirmative)
| Person | Form |
|---|---|
| tú | diagnostica |
| él/ella/Ud. | diagnostique |
| nosotros/as | diagnostiquemos |
| vosotros/as | diagnosticad |
| ellos/ellas/Uds. | diagnostiquen |
Imperative (negative)
| Person | Form |
|---|---|
| tú | diagnostiques |
| él/ella/Ud. | diagnostique |
| nosotros/as | diagnostiquemos |
| vosotros/as | diagnostiquéis |
| ellos/ellas/Uds. | diagnostiquen |
Gerund and past participle
| Form | Spanish | Use |
|---|---|---|
| Gerund | diagnosticando | with estar for the progressive: estoy diagnosticando |
| Past participle | diagnosticado | with haber for the perfect tenses: he diagnosticado |
How to use each tense
Present indicative
Use the present for routines, general facts and what is happening right now. It is the tense you will use most often in everyday conversation, for habits with words like todos los días and for statements that are true in general. For diagnosticar, the present indicative looks like this in a real sentence: Yo diagnostico a tiempo — "I diagnose in time". Learn the present indicative forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Preterite
Use the preterite for finished actions in the past — things that started and ended, often with time words like ayer, anoche or la semana pasada. The preterite moves a story forward, one completed event at a time. For diagnosticar, the preterite looks like this in a real sentence: Yo diagnostiqué el problema — "I diagnosed the problem". Learn the preterite forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense. Spelling change in the preterite: the yo form is diagnostiqué (c → qu before e), so the sound of the stem stays the same.
Imperfect
Use the imperfect for background, habits and actions in progress in the past, often with words like antes, de niño or mientras. It describes how things used to be, not one finished event. For diagnosticar, the imperfect looks like this in a real sentence: Yo diagnosticaba la enfermedad — "I used to diagnose the illness". Learn the imperfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Future
Use the future for plans, predictions and promises, often with mañana, el año que viene or pronto. It talks about what will happen, not what is happening now. For diagnosticar, the future looks like this in a real sentence: Yo diagnosticaré a tiempo — "I will diagnose in time". Learn the future forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Conditional
Use the conditional for polite requests, hypotheticals and what would happen, often in si clauses. It softens a request and describes imagined situations. For diagnosticar, the conditional looks like this in a real sentence: Yo diagnosticaría el problema — "I would diagnose the problem". Learn the conditional forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Present perfect
Use the present perfect for recent actions and experiences, often with hoy, esta semana or ya. It connects the past with the present moment. For diagnosticar, the present perfect looks like this in a real sentence: Yo he diagnosticado la enfermedad — "I have diagnosed the illness". Learn the present perfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Pluperfect
Use the pluperfect when one past action happened before another past action. It is the past of the past, and it usually appears with antes de or ya. For diagnosticar, the pluperfect looks like this in a real sentence: Yo había diagnosticado a tiempo — "I had diagnosed in time". Learn the pluperfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Future perfect
Use the future perfect for something that will already be finished by a future time, often with para mañana or para el viernes. For diagnosticar, the future perfect looks like this in a real sentence: Yo habré diagnosticado el problema — "I will have diagnosed the problem". Learn the future perfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Conditional perfect
Use the conditional perfect for what would have happened under different conditions. It looks back at a past that never happened. For diagnosticar, the conditional perfect looks like this in a real sentence: Yo habría diagnosticado la enfermedad — "I would have diagnosed the illness". Learn the conditional perfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Present subjunctive
Use the present subjunctive after expressions of wish, doubt, emotion and hope, such as espero que or quiero que. The subjunctive does not state a fact; it states an attitude towards the action. For diagnosticar, the present subjunctive looks like this in a real sentence: Espero que él diagnostique a tiempo — "I hope he diagnoses in time". Learn the present subjunctive forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense. The subjunctive keeps the spelling change: diagnostique, diagnostiques, diagnostique all show c → qu before e, just like the preterite yo form.
Imperfect subjunctive (-ra)
Use the imperfect subjunctive after past wishes and in si clauses about the past, and note the -ra forms shown here; the -se forms use the same stem. For diagnosticar, the imperfect subjunctive (-ra) looks like this in a real sentence: Si yo diagnosticara el problema, todo cambiaría — "If I diagnosed the problem, everything would change". Learn the imperfect subjunctive (-ra) forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Imperative (affirmative)
Use the affirmative imperative for direct commands, instructions and invitations. It tells someone to do something, and it has no yo form. For diagnosticar, the imperative (affirmative) looks like this in a real sentence: Diagnostique la enfermedad — "Let him diagnose the illness". Learn the imperative (affirmative) forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Imperative (negative)
Use the negative imperative, always with no, to tell someone not to do something. It uses the subjunctive forms, so it looks different from the affirmative commands. For diagnosticar, the imperative (negative) looks like this in a real sentence: No diagnostiques a tiempo — "Don't diagnose in time". Learn the imperative (negative) forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.
Example sentences
Ten natural sentences with diagnosticar, covering different tenses and persons. Each one uses a form from the tables above.
- Yo diagnostico el problema — "I diagnose the problem"
- Él diagnostica la enfermedad — "He diagnoses the illness"
- Yo diagnostiqué a tiempo — "I diagnosed in time"
- Yo diagnosticaba el problema — "I used to diagnose the problem"
- Tú diagnosticarás la enfermedad — "You will diagnose the illness"
- Yo diagnosticaría a tiempo — "I would diagnose in time"
- Él ha diagnosticado el problema — "He has diagnosed the problem"
- Espero que él diagnostique la enfermedad — "I hope he diagnoses the illness"
- Yo había diagnosticado a tiempo — "I had diagnosed in time"
- Ellos diagnosticaban el problema — "They used to diagnose the problem"
Common mistakes
- Wrong: Ellos diagnostica la enfermedad — Right: Ellos diagnostican la enfermedad — Ellos needs the ellos form diagnostican. The singular diagnostica belongs with él, ella or a singular noun.
- Wrong: Ayer, yo diagnostico — Right: Ayer, yo diagnostiqué — The present tense cannot describe a finished action yesterday. Ayer forces the preterite, so the form must change to diagnostiqué, with the spelling change c → qu before e.
- Wrong: De niño, yo diagnostiqué todos los días. — Right: Todos los días, yo diagnosticaba — For a repeated habit in the past, use the imperfect (diagnosticaba), not the preterite. The preterite (diagnostiqué) is for one finished action.
- Wrong: Yo soy diagnosticado a tiempo. — Right: Yo he diagnosticado a tiempo. — Spanish perfect tenses use haber, not ser: he diagnosticado, has diagnosticado, ha diagnosticado. Ser plus the participle makes a passive, not a perfect tense.
- Wrong: Espero que él diagnostica la enfermedad. — Right: Espero que él diagnostique la enfermedad. — After espero que, Spanish needs the subjunctive: diagnostique. The indicative diagnostica is wrong here.
Quiz: test yourself
Ten questions on diagnosticar. Choose the right form, then check the answer key below.
Complete the sentence: Yo ___ la enfermedad. (present tense) A. habría diagnosticado B. diagnostico C. diagnostiquéis D. ha diagnosticado
Complete the sentence: Él ___ la enfermedad. (preterite) A. diagnostiquen B. habéis diagnosticado C. diagnosticó D. diagnostiqué
Complete the sentence: Nosotros ___ la enfermedad. (imperfect) A. habrían diagnosticado B. diagnosticaríais C. ha diagnosticado D. diagnosticábamos
Complete the sentence: Tú ___ la enfermedad. (future) A. diagnosticarás B. habrían diagnosticado C. diagnostiques D. diagnosticaríais
Complete the sentence: Yo ___ la enfermedad. (conditional) A. diagnosticaría B. diagnosticad C. habrá diagnosticado D. habré diagnosticado
Complete the sentence: Espero que él ___ la enfermedad. (present subjunctive) A. habréis diagnosticado B. habéis diagnosticado C. diagnostique D. diagnosticaban
Complete the sentence: Si yo ___ la enfermedad, todo cambiaría. (imperfect subjunctive, -ra form) A. diagnosticara B. diagnosticaríamos C. diagnosticará D. diagnosticas
Complete the sentence: Nosotros ___ la enfermedad. (present perfect) A. diagnosticaríais B. diagnosticaste C. hemos diagnosticado D. diagnosticas
Complete the command: No ___ la enfermedad. (negative imperative, tú) A. diagnostiquemos B. diagnostiquéis C. diagnostiquen D. diagnostiques
Which is the gerund of diagnosticar, used with estar for the progressive? A. diagnosticando B. diagnosticado C. diagnosticaré D. diagnostico
Answer key
- diagnostico — The yo present tense of diagnosticar is diagnostico.
- diagnosticó — The él/ella/Ud. preterite of diagnosticar is diagnosticó.
- diagnosticábamos — The nosotros/as imperfect of diagnosticar is diagnosticábamos.
- diagnosticarás — The tú future of diagnosticar is diagnosticarás.
- diagnosticaría — The yo conditional of diagnosticar is diagnosticaría.
- diagnostique — The él/ella/Ud. present subjunctive of diagnosticar is diagnostique.
- diagnosticara — The yo imperfect subjunctive, -ra form of diagnosticar is diagnosticara.
- hemos diagnosticado — The nosotros/as present perfect of diagnosticar is hemos diagnosticado.
- diagnostiques — The negative tú imperative uses the present subjunctive form with no before it: diagnostiques.
- diagnosticando — The gerund of diagnosticar is diagnosticando: estoy diagnosticando. The participle diagnosticado is used with haber instead.
Frequently asked questions
What does diagnosticar mean in English?
Diagnosticar means to diagnose. It is used in everyday situations such as Yo diagnostico la enfermedad. The exact English wording depends on the context, but the core meaning stays the same across the tenses.
Is diagnosticar regular?
Mostly. Diagnosticar follows the regular -ar endings, but it has a spelling change (c → qu before e). The tables on this page show every form, so you can see exactly where the spelling changes.
What is the gerund and the past participle of diagnosticar?
The gerund is diagnosticando, used with estar for the progressive: estoy diagnosticando. The past participle is diagnosticado, used with haber in the perfect tenses: he diagnosticado.
How do I say “I diagnose” in the past?
It depends on the kind of past. For one finished action, use the preterite: Yo diagnostiqué a tiempo. For a repeated habit or background in the past, use the imperfect: Yo diagnosticaba el problema. For something that has just happened, use the present perfect: Yo he diagnosticado la enfermedad.
How do I practise diagnosticar?
Start with the present tense table, then drill the preterite and the imperfect, since those two past tenses cause the most mistakes. Try the diagnosticar examples and quiz page for more sentences, and use the Spanish Verb Quiz to test the forms under pressure.
Related links
- Diagnosticar in the present tense — the full present-tense table for diagnosticar.
- Diagnosticar examples and quiz — more example sentences and practice for diagnosticar.
- Spanish verbs — the Spanish hub, with every verb and tense guide.
- Operar conjugation — another -ar verb to compare with diagnosticar.
- Recetar conjugation — another -ar verb to compare with diagnosticar.
- Rascar conjugation — another -ar verb to compare with diagnosticar.
- Spanish Verb Quiz — test yourself on real conjugated forms.
- Verb Conjugator — conjugate any Spanish verb in every tense.