Introduction

Diagnosticar means “to diagnose”, and this page covers exactly one thing: diagnosticar in the present tense. The present is the tense Spanish speakers reach for when they talk about what happens regularly and what is happening now. On this page you will find the full present table for diagnosticar, how the tense is formed for this verb, the situations where it is used, how it differs from the preterite, worked examples, the mistakes learners make most often, an eight-question quiz with explained answers, and answers to the questions students ask about diagnosticar in the present. Diagnosticar in the present describes a habit, a fact or something happening right now. For example: “Yo diagnostico la enfermedad” — "I diagnose the illness". Everything on this page uses the forms of diagnosticar exactly as they are conjugated in the present, so you can trust every form you see here.

Diagnosticar in the Present Tense — full table

Person Form
yo diagnostico
tú diagnosticas
él/ella/Ud. diagnostica
nosotros/as diagnosticamos
vosotros/as diagnosticáis
ellos/ellas/Uds. diagnostican

Gerund: diagnosticando · Past participle: diagnosticado

The gerund is diagnosticando, which you use with estar to say what is happening right now: “Estoy diagnosticando” means the action of diagnosticar is in progress at this very moment. The past participle is diagnosticado, which you use with haber in the perfect tenses: “he diagnosticado” is the present perfect, used for a completed action. Keep both forms in mind as you read the examples below, because the present is only one part of how diagnosticar is used.

How the present of diagnosticar is formed

Diagnosticar is a spelling-changing -ar (c → qu before e) verb in the present. Take the stem diagnostic and add the present endings for -ar verbs: -o, -as, -a, -amos, -áis, -an, giving diagnostico, diagnosticas, diagnostica, diagnosticamos, diagnosticáis, diagnostican. Watch the accents: the vosotros form, diagnosticáis, carries an accent on the á, é or í. The present of diagnosticar is regular in its endings, but two details deserve attention. First, the accents: the vosotros form diagnosticáis carries a written accent. Second, the yo form diagnostico is the form the present subjunctive is built from, so learn it well — it unlocks the subjunctive too.

When to use the present of diagnosticar

The present is not a single-purpose tense. Below are the five situations where you will use diagnosticar in the present most often. Each one comes with a real example, so read the rule, then say the example out loud.

1. Routines and habits

The present is the tense of what you do regularly. When something happens todos los días, cada semana or los fines de semana, diagnosticar goes in the present. Example: “Yo diagnostico a tiempo” — "I diagnose in time".

2. General facts

Use the present for things that are true in general, not just today. A fact about diagnosticar does not need a time word at all. Example: “Él diagnostica el problema” — "He diagnoses the problem".

3. What is happening now

The present also covers what is happening at this very moment. Spanish often uses the simple present where English would use the -ing form, so diagnostico can mean both "I diagnose" and "I am diagnosing". Example: “Yo diagnostico la enfermedad” — "I diagnose the illness".

4. Timetables and fixed plans

For a fixed plan or a timetable, Spanish uses the present: the plan is already decided, so the present states it as a fact. This is common with travel, lessons and appointments. Example: “Nosotros diagnosticamos a tiempo” — "We diagnose in time".

5. Telling a story

Stories are sometimes told in the present to make them feel immediate, even when they happened in the past. This is the historical present, and it works with diagnosticar just as it does with any other verb. Example: “Él diagnostica el problema” — "He diagnoses the problem".

Present Tense vs Preterite: how to choose

The closest tense to the present is the preterite, and choosing between them is one of the first decisions in Spanish. The rule is simple: the present reports what happens regularly or what is happening now, while the preterite reports one finished action in the past. The three pairs below use the same verb, so the only thing that changes is whether the action is a habit or a finished event. Time words help: todos los días and cada semana point to the present, while ayer and la semana pasada point to the preterite.

  • Present Tense: “Yo diagnostico la enfermedad” — "I diagnose the illness".

  • Preterite: “Yo diagnostiqué la enfermedad” — "I diagnosed the illness".

  • The present sentence describes a habit or something happening now; the preterite sentence reports one finished action in the past. That difference — routine versus finished event — is the whole decision.

  • Present Tense: “Él diagnostica a tiempo” — "He diagnoses in time".

  • Preterite: “Él diagnosticó a tiempo” — "He diagnosed in time".

  • The present sentence describes a habit or something happening now; the preterite sentence reports one finished action in the past. That difference — routine versus finished event — is the whole decision.

  • Present Tense: “Nosotros diagnosticamos el problema” — "We diagnose the problem".

  • Preterite: “Nosotros diagnosticamos el problema” — "We diagnosed the problem".

  • The two sentences look identical: diagnosticamos is the same in the present and the preterite. Only the time words around it tell you which tense is meant.

Example sentences: diagnosticar in the present

Read these eight sentences out loud. They cover all six persons, so by the end you will have seen every form in the table used in a real sentence. Pay attention to the words around the verb — the time expressions, the objects, the other verbs — because those are what make each sentence sound natural.

  1. “Yo diagnostico a tiempo” — "I diagnose in time"

  2. “Tú diagnosticas el problema” — "You diagnose the problem"

  3. “Él diagnostica la enfermedad” — "He diagnoses the illness"

  4. “Nosotros diagnosticamos a tiempo” — "We diagnose in time"

  5. “Vosotros diagnosticáis el problema” — "You diagnose the problem"

  6. “Ellos diagnostican la enfermedad” — "They diagnose the illness"

  7. “Yo diagnostico a tiempo” — "I diagnose in time"

  8. “Él diagnostica el problema” — "He diagnoses the problem"

Common mistakes with diagnosticar in the present

These are the errors learners actually make with this verb in this tense. Each one shows the wrong version, the right version, and why the correction matters.

  • Wrong: “Ellos diagnostica la enfermedad” Right: “Ellos diagnostican la enfermedad” Why: Ellos needs the ellos form diagnostican. The singular diagnostica belongs with él, ella or a singular noun.

  • Wrong: “Todos los días, yo diagnostiqué” Right: “Todos los días, yo diagnostico” Why: Todos los días describes a habit, so the present is right. The preterite (diagnostiqué) is for one finished action, not for routines.

  • Wrong: “Yo diagnostica la enfermedad.” Right: “Yo diagnostico la enfermedad” Why: Yo needs the yo form diagnostico. The él form diagnostica belongs with él, ella or a singular noun.

  • Wrong: “Ayer, yo diagnostico” Right: “Ayer, yo diagnostiqué” Why: The present tense cannot describe a finished action yesterday. Ayer forces the preterite, so the form must change to diagnostiqué.

Quiz: diagnosticar in the present

Choose the correct answer for each question, then check the answer key. Every answer is explained, so a wrong answer still teaches you something.

1. Complete the sentence: “Yo ___ el problema.” (yo form)

A. diagnostico B. diagnosticas C. diagnostica D. diagnosticáis

2. Complete the sentence: “Tú ___ la enfermedad.” (tú form)

A. diagnostico B. diagnosticas C. diagnostica D. diagnosticáis

3. Complete the sentence: “Él ___ a tiempo.” (él/ella/Ud. form)

A. diagnostica B. diagnosticáis C. diagnostico D. diagnosticamos

4. Complete the sentence: “Nosotros ___ el problema.” (nosotros/as form)

A. diagnostican B. diagnostico C. diagnosticas D. diagnosticamos

5. Complete the sentence: “Vosotros ___ la enfermedad.” (vosotros/as form)

A. diagnostican B. diagnosticáis C. diagnosticas D. diagnostico

6. Complete the sentence: “Ellos ___ a tiempo.” (ellos/ellas/Uds. form)

A. diagnostico B. diagnosticas C. diagnosticamos D. diagnostican

7. Which time expression points to the present tense?

A. todos los días B. ayer C. la semana pasada D. anoche

8. Which sentence is correct?

A. Todos los días, yo diagnostico B. Todos los días, yo diagnostiqué

Answer key

  1. diagnostico — The yo present of diagnosticar is diagnostico.
  2. diagnosticas — The tú present of diagnosticar is diagnosticas.
  3. diagnostica — The él/ella/Ud. present of diagnosticar is diagnostica.
  4. diagnosticamos — The nosotros/as present of diagnosticar is diagnosticamos.
  5. diagnosticáis — The vosotros/as present of diagnosticar is diagnosticáis.
  6. diagnostican — The ellos/ellas/Uds. present of diagnosticar is diagnostican.
  7. todos los días — Todos los días describes a habit, so the present is right. Ayer, la semana pasada and anoche all point to the preterite.
  8. Todos los días, yo diagnostico — Todos los días is a habit, so the present is correct. The preterite is for one finished action.

Frequently asked questions

When do I use the present of diagnosticar?

Use the present for routines, general facts and what is happening now. For example: Yo diagnostico la enfermedad. If the action is a habit or happening now, the present is the right choice.

How is the present of diagnosticar formed?

Take the stem diagnostic- and add the present endings for -ar verbs (-o, -as, -a, -amos, -áis, -an), giving diagnostico, diagnosticas, diagnostica, diagnosticamos, diagnosticáis, diagnostican.

What is the difference between the present and the preterite for diagnosticar?

The present (diagnostico) describes a habit or something happening now, while the preterite (diagnostiqué) counts one finished action in the past. Compare the two sentences in the contrast section above: the verb is the same, only the tense changes.

How can I practise diagnosticar in the present?

Say the six forms out loud — diagnostico, diagnosticas, diagnostica, diagnosticamos, diagnosticáis, diagnostican — then use them in the example sentences above, changing the person each time. Then try the diagnosticar examples and quiz page, and the full conjugation of diagnosticar when you want to compare the present with the other tenses.

Related links