The type of Diphtheria with highest mortality is
Clinical manifestations of diphtheria 
1. Faucial (tonsillo pharyngeal) diphtheria

It is the commonest type of diphtherial infection.
Incubation period is 2-5 days.
Patients present with malaise, sore throat and moderate fever.
A thick adherent pseudomnembrane (gray or white) is present on one or both tonsils or adjacent pharynx.
Dislodging the membrane is likely to cause bleeding.
A small percentage of patients present with massive swelling of the tonsils and uvula with cervical lymphadenopathy (bull neck) and severe toxemia → Malignant diphtheria.
Systemic toxicity (toxemia) is usually most severe when pseudomembrane extends from tonsil and pharynx (faucial diphtheria) to adjacent areas.

2. Laryngeal diphtheria

Presents as hoarseness and cough.
It is the most severe form of respiratory diphtheria.
Trocheostomy may be required.

3.Nasal diphtheria

Presents with unilateral or bilateral nasal discharge.
Mildest form of respiratory diphtheria

4. Cutaneous diphtheria

Caused by nontoxigenic strains
Presents as distinct "punched out" ulcers.
More common in tropical areas.
Other less common type of diphtheria are conjunctiva, otitic, genital - (vulval, vaginal or prepucial), gastrointestinal.
Pharyngeal
Nasal
Laryngeal
Conjuntival