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Exhibit 31.1 Certification of Chief Executive Officer
pursuant to Section 302 of the
Sarbanes-Oxley Act of 2002 I, David B. Kaysen, certify that: 1. I have reviewed this annual report on Form 10-K of Diametrics Medical,
Inc.; 2. Based on my knowledge, this report does not contain any untrue statement
of a material fact or omit to state a material fact necessary to make the statements made,
in light of the circumstances under which such statements were made, not misleading with
respect to the period covered by this report; 3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material respects the financial
condition, results of operations and cash flows of the registrant as of, and for, the
periods presented in this report; 4. The registrants other certifying officer(s) and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in Exchange Act
Rules 13a-15(e) and 15d-15(e)) and internal control over
financial reporting (as
defined in Exchange Act Rules 13a-15(f) and 15(d)-15(f)) for the registrant and have: (a) Designed such disclosure controls and procedures, or caused such disclosure
controls and procedures to be designed under our supervision, to ensure that
material information relating to the registrant, including its consolidated
subsidiaries, is made known to us by others within those entities, particularly
during the period in which this report is being prepared; (b)
Designed such internal control over financial reporting, or caused
such internal control over financial reporting to be designed under
our supervision, to provide reasonable assurance regarding the
reliability of financial reporting and the preparation of financial
statements for external purposes in accordance with generally accepted
accounting principles; (c) Evaluated the effectiveness of the registrants disclosure controls and
procedures and presented in this report our conclusions about the effectiveness of
the disclosure controls and procedures, as of the end of the period covered by this
report based on such evaluation; and (d) Disclosed in this report any change in the registrants internal control
over financial reporting that occurred during the registrants most recent fiscal
quarter (the registrants fourth fiscal quarter in the case of an annual report)
that has materially affected, or is reasonably likely to materially affect, the
registrants internal control over financial reporting; and 5. The registrants other certifying officer(s) and I have disclosed, based
on our most recent evaluation of internal control over financial reporting, to the
registrants auditors and the audit committee of the registrants board of directors (or
persons performing the equivalent functions): (a) All significant deficiencies and material weaknesses in the design or
operation of internal control over financial reporting which are reasonably likely
to adversely affect the registrants ability to record, process, summarize and
report financial information; and (b) Any fraud, whether or not material, that involves management or other
employees who have a significant role in the registrants internal control over
financial reporting. Date: May 5, 2005 /s/ David B. KaysenSignatureName:
    David B. KaysenTitle:
    Chief Executive Officer